Cavendish, 26, has already decided which team he will be joining in 2012 but has so far refused to reveal their identity.
The current HTC-Highroad rider has been heavily linked with a switch to Team Sky when his current contract expires and Thomas is keen for Cavendish to join him.
"It's a tricky decision for him, but I hope he comes here," Thomas told BBC Sport Wales.
"We've got a good relationship, we're good mates and he's got a lot of mates in Sky and he can see it's a good team.
"He's the fastest man in the world and to be leading him out would be great.
"As they say success breeds success and if we were leading him out and he's winning stages in the biggest races then it will carry the whole team forward."
Cavendish has one 20 stages of the Tour De France in his career.