Number eight Jones, winger Williams and centre Will Greenwood scored tries at the 'House of Pain', while fly-half Charlie Hodgson pressed his Test match claims by kicking 15 points.
Jones was only called up by Sir Clive Woodward to join the tourists after Simon Taylor was ruled out of the series against New Zealand with a hamstring injury.
But Williams believes enjoying the rugby is the key to Jones following up his success for Wales with the Lions.
He told Sky Sports News: "Considering he [Jones] has not been here long, maybe it is a little bit surprising.
"But he has been performing like that all season, that's the way he plays week-in week-out so it's not surprising really.
"As soon as one player starts enjoying himself, the whole 15 start enjoying themselves. When we start chucking the ball around a bit it's a fun game to play. We did that in the second half and thoroughly deserved to win the game.
"Enjoyment - that was the key to success in the Six Nations, all the boys enjoyed playing rugby together. There was a fizz among the team and the squad and that is certainly here at the moment.
"I'm enjoying my rugby at the moment, I'm excited to be here and the boys are the same. It shows on the field."