Since arriving at the club in February Grayson has not tasted defeat in front of his home fans, and Jeffrey Monakana's strike just before half-time helped them win their final home game of the season 1-0.
Grayson insists it is the least their fans deserve as Preston stretched their unbeaten run to four games with just two left to play.
"What we've said for the last couple of weeks is we want to finish the season in a positive manner and send the supporters home from Deepdale happy with what they've seen," he said.
"They've shown a fantastic attitude in wanting to win a game, working hard for the club and the shirt and showed some good quality at times.
"It's a positive place to be now we've finished the season at home and I'm delighted we got another win and another clean sheet and won the game in a comfortable, professional manner I would say.
"From the second-half I thought we were quite comfortable. I thought we controlled the game really.
"It would have been nice to have got another couple of goals but it's a clean sheet, a victory and sending the supporters home in a happy mood.
"Hopefully that will continue for a long time. We're really working hard on the training pitch."
Monakana struck in first-half injury time to settle the game, grabbing his fourth league goal of the season as he rifled home from 12 yards out.