The Sky Blues looked set to claim the points after striker Leon Clarke opened the scoring against his old club six minutes into the second half.
Yaser Kasim equalised for the hosts 13 minutes from time before substitute Miles Storey grabbed the winner for the Robins four minutes from time.
"Since coming to the club the opening 45 minutes from us was as good as you're likely to see," said Pressley after Coventry's 2-1 loss at the County Ground.
"Make no mistake we played against a side that dominates at home yet we were magnificent and always looked a threat.
"We hit the bar and the post and were incredibly unlucky because the game was as good as a standard as I've seen at League One level.
"If we give more performances like that we'll win plenty of games, no doubt about it, and our brilliant travelling support could see it from their reaction after the game. They knew how much the players gave.
"Some of the football we played was sensational. Our passing was quick and aggressive, our pressing was top level and it's exactly the type of football I want to see. It was a brilliant performance but we have nothing to show for it."