Bath geared up for 'one-off' Challenge Cup final
Van Graan's side have already clinched a home semi-final in the league, on June 6, with one game of the regular season to play.
They are eyeing a potential treble this campaign with Friday's continental decider coming two months after the Premiership Cup success.
"I don't see tomorrow night's clash having anything to do with the Premiership," South African Van Graan told reporters.
"For us, it's a moment in time, it's 80 minutes, it's a European final, so that's the way that we've gone the whole season.
"It's a one-off," the 45-year-old added.
Former Springboks assistant coach Van Graan took over Bath in 2022 and has turned their fortunes around.
In the campaign prior to his arrival, the former European champions, who were founded back in 1865, finished bottom of the Premiership table but avoided dropping down to the second-tier Championship with relegation temporarily suspended.
Last season, Van Graan took Bath to a Premiership final having finished second in the table.
"The fact that we've played in a Premiership final, and a Premiership Cup final, and now a European final, are great experiences for us as a group," Van Graan said.
"I think the good thing about the group is to just keep it simple, just be ourselves," he added.
Bath's chances of the club's first treble and maiden continental title since the 2008 Challenge Cup could come down to influential fly-half Scotland Finn Russell, who was named in the British and Irish Lions squad earlier this month.
Russell, 32, joined Bath in 2023 having spent five years at French club Racing 92.
"We've studied that a lot this week," Lyon captain Baptiste Couilloud told reporters earlier in the day.
"He's someone we were used to playing in our league.
"We know the threat he poses," the scrum-half added.