Just to clarify, it isn't "based on" the Rothmans livery per se.
It is the Rothmans livery, just with the 'Racing' logo retrofitted to comply with tobacco advertising laws in the country where it competed at that time. Sometimes this is done long after race cars are retired from competition, so that teams can use it as a show car without worrying about potential law suits or further censorship.
In any case I can nearly 100% guarantee that you will not see the word 'Rothmans' on the car in-game. It is for the same reason that you don't see the words 'Silk Cut' emblazoned on the Jaguar XJR-9 in-game.