Gray, put in temporary charge in early December following the sacking of Dave Jones, has lifted resurgent Wednesday out of the relegation zone and rates this latest triumph as the high point of his coaching career.
Reda Johnson and Atdhe Nuhiu put Wednesday in control with first-half goals and, after Leeds substitute Matt Smith was sent off for his aerial challenge on Johnson seconds into the second half, the floodgates opened at Hillsborough.
Connor Wickham slammed home the third, Chris Maguire followed up with a deflected free-kick and substitute Caolan Lavery fired a superb late double to seal Wednesday's biggest win against their White Rose rivals.
"I've got to sit down and have a glass of wine with the chairman after I've finished with you guys," said former Northampton and Southampton manager Gray in his press conference.
"(It was) a good result and a good performance, hopefully a 6-0 win will help me to get the job.
"I remember I was caretaker at Southampton and our last two games at The Dell we beat Arsenal and Manchester United, so it's probably up there with those. And I got the job."
When told chairman Mandaric had still to make his mind up over the managerial vacancy, Gray added: "I'll have a glass of wine, but he might not mention the job then.
"He might come and see me (on Sunday), we're in training, but I want to enjoy this moment because it doesn't happen many times in your playing, managing or coaching career."
Wednesday have won four and drawn three of their eight league games under Gray and this win could have been even bigger as Liam Palmer spurned a golden chance before half-time, while substitute Jermaine Johnson hit the post.
"On the back of the Blackpool win when we played very well, I said to the players can you repeat that again?" Gray added. "Can you do it for 90 minutes?
"All credit to the players. Results are the most important thing, but can you get a performance to go with it?
"Not many times during a season do you get the perfect result and the perfect performance. Every player put in an eight or nine out of 10 performance.
"We put Leeds on the back foot. We got two goals up, you could see the confidence in the team. We didn't take our foot off the gas and credit to the players for that. Our finishing was clinical."