Grayson's North End team dominated the first half but only had Joe Garner's glancing header on the stroke of half-time to show for their efforts as they held a narrow lead.
And the U's made them pay as they missed chance after chance when Luke Garbutt's first league goal for the club earned the visitors a share of the points.
Promotion-chasing Preston's unbeaten run stretched to seven games in all competitions but Grayson was sure it should have been so much more.
"I'm devastated," said the Deepdale boss. "Anyone who was here has seen us draw a game when we could have won three or four games with the chances we had.
"We have had 28 attempts on goal but have only scored once, which is so frustrating.
"I have been in games like this before when you can sometimes sense it that if you don't get that second goal.
"We could have won the game by double figures but you have to be ruthless and make sure that you punish teams. We weren't ruthless enough.
"I have never managed a game when we have had so many chances and not won the game. We were gob-smacked in the dressing room.
"Kevin Davies has probably never missed so many chances in the six-yard box."
"There were a lot of good points from the game though and that is what you have got to draw from.
"If we play like that against most teams in this division, we will win more points than we drop."
- Sports & Recreation
- Luke Garbutt