Grayson was appointed as North End's new manager on Monday, when it was confirmed Glyn Snodin, his number two at Leeds and Huddersfield, would be installed as assistant boss.
John Dreyer, a member of the coaching team Graham Westley brought to Deepdale last January, took caretaker charge for the Lilywhites' 2-0 win over Bournemouth last weekend and he will retain his coaching role as Grayson looks to gain a full understanding of his inherited squad
"Glyn's somebody I've known since I was 17 at Leeds - I was an apprentice, he was there as a first-team player," he said.
"He's got the experience of working at Charlton, West Ham and Southampton, assistant manager at Northern Ireland. It was a great experience having him with me at Leeds and Huddersfield."
On Dreyer, Grayson added: "I think it's important for John to stay on because he's a good football man, he knows about the football club and it would be a bit remiss of me to go in cold and not know anything about what makes the players tick.
"He's obviously seen them. He knows the good points of them, the bad points of them and I'm looking forward to working with him."