United's progress under David Weir's stewardship continued with a point in Saturday's home game.
However, the Blades had to hit back from a first half setback with Freddie Sears giving Colchester the lead.
Harry Maguire, though, netted his second goal of the season with a 30-yard shot, which was helped considerably by a mistake from visiting goalkeeper, Sam Walker.
Manager Weir made three changes to his starting line-up, McMahon came in for his first start of the season, McGinty was handed a debut and McFadzean was recalled. There were also changes on the bench, as well as Westlake and McGinn, Johns, a summer recruit, and 17-year-old Academy striker, Eyre, were part of the squad.
McMahon and McGinty slotted into the full-back roles, whilst early in the encounter it appeared that McFadzean was operating the advanced role in front of the central midfield duo of Coady and Doyle.
United's keep possession philosophy was evident again from the opening minutes and it resulted in the first chance. A very patient build up involving Maguire, Collins, Doyle, Murphy, McFadzean and Brandy saw McMahon cut in and curl just wide with his left foot. McMahon also hit a 35-yard free-kick which was wide.
The signs were encouraging. McFadzean almost connected with a Brandy cross, whilst the latter was inches away from nudging home a McMahon centre.
Then, on 25 minutes, McGinty's header from McMahon's cross earned United a corner, from which Colchester capitalised. The visitors broke out of defence and found themselves with a three-on-two situation and Watt timed his pass to allow SEARS to slot past Long and into the corner of the net.
Colchester had an opportunity to add to their tally soon after when Eastmond's free-kick was flashed back across goal by Eastman and then Dickson long-range shot was just wide.
Coady picked up the game's first booking as half-time approached, following a foul, but the Blades did get back on level terms before the interval, with a little help from the visiting goalkeeper. From another patient build up, a foul in midfield allowed Brandy to take a quick set-piece, laying off to MAGUIRE, whose 30-yard shot was fumbled by Walker into his own net.
Colchester won a couple of free-kicks in injury-time at the end of the first half but felt aggrieved that they should have had another when referee Clark blew his whistle for the interval, which resulted in Watt picking up a booking.
The Blades began the second period well and the first two opportunities were created by McMahon. He delivered the throw from which Taylor's shot on the turn was saved by Walker and then clipped in the free-kick which saw Coady's header also collected by the visiting goalkeeper.
Colchester thought they had regained the lead on 55 minutes but a flag was up against Ibehre, who turned home Dickson's free-kick, whilst the Blades also went close to grabbing the lead on the hour when Brandy threaded the ball through the defence for Taylor but Walker was quickly off his line to save with his legs.
Maguire was booked for kicking the ball away after a foul and Johns was another to be handed a debut when he replaced McFadzean for the final 15 minutes. Brandy was causing Colchester problems but the visitors were also showing intent to search for a winner, which resulted in Johns picking up a booking to stop another move.
In the final ten minutes, from a Blades corner, Okuonghae and Maguire fell in a heap but the latter still managed to turn the ball just wide, the centre half also had a half-volley blocked following a McMahon free-kick.
As the clock ticked around to 90 minutes, the Blades also had a 'goal' ruled out for offside when Taylor slotted home a deflected Brandy shot, whilst three added minutes in injury-time could not produce a winner.
Blades: Long, Maguire, Doyle, Taylor, Collins, Coady, Brandy, McGinty, Murphy, McFadzean (Johns 75), McMahon.
Unused: Howard, Westlake, Hill, Porter, McGinn, Johns, Eyre.
Colchester: Walker, Da Wright, Dickson, Okuonghae, Eastmond, Watt (Dr Wright 61), Sears (Bond 66), Ibehre (Morrison 80), Eastman, Wilson, Massey.
Unused: Cousins, Thompson, Bean, Gilbey.