North End, who won it through Joe Garner's first-half stunner, became the first side to beat Orient at Brisbane Road this season and also stopped them scoring for the first time.
And Grayson insists the win was planned on the training ground.
"They did everything that I asked them to do from first thing on Monday morning until 5 o'clock, they had to put bodies on the line and they had to work for each other," he said.
"That was the thing that we made very clear to the players when we started our preparations for this game.
"When you look at the overall play, we were very god from start to finish. In the first half, I thought we were very disciplined and controlled the game, passed the ball around well and Orient rarely threatened us in that period.
"It was a great goal from Joe Garner that put us in front and then you expect Orient to come at you because they are a good team, they are not at the top of the division for no reason.
"But when we had to battle and scrap and make last-ditch challenges, we did that. Orient work you extremely hard, they close you down and stop you playing and we had to be better than them at doing that.
"Every one of our players worked so hard for the team and contributed in a fantastic way."
Garner struck a superb first-time volley high into the roof of the net after 32 minutes to record what proved the only goal of a tight-affair at Brisbane Road where a crowd of 7,123, Orient's highest attendance of the campaign, saw them lose their unbeaten home league run stretching back to February.
While Orient created little in the first half, they improved markedly after the break forcing their opponents to pack their defensive ranks. David Mooney and substitute Robbie Simpson both had chances to equalise but the resilient visitors' defence stuck resolutely to their task to protect their slender but deserved lead.
The defeat also saw the O' forfeit top-spot to Wolves while fourth-placed Preston sustained their own promotion hopes.
Orient boss Russell Slade acknowledged the quality of the strike that beat his side.
"They've got players who have played a higher level and that was a wonderful finish from a Championship player," he said.
"I thought that they bossed the game a bit in the first period and made life very difficult for us, slowed the game down and dictated the tempo and ran the officials as well to be honest.
"I'm a bit disappointed that we didn't create more chances but they didn't create too much either, it was a cagey game with very little between the teams.
"We grew into the game and ground it down and I thought we finished the stronger side for sure and had a wonderful window of opportunity to get the equaliser right at the end but we didn't take it.
"We knew that it was going to be a tough game, it was first against fourth and they set their stall out fairly negatively. They weren't going to go forward too much, they had five at the back for most of the second-half am d they proved difficult and resilient to break down. Simon's team are like that."