The 20-year-old has been linked with a number of Premier League clubs following his performances for the Sky Blues last season, when he scored nine goals in all competitions - including the winner in the EFL Trophy final against Oxford United at Wembley.
The likes of Leicester City, Newcastle United and Brighton & Hove Albion are all understood to be keeping tabs on the youngster, but The Independent reports that Swansea are currently the frontrunners to secure his signature.
Thomas played for Wales Under-20s at the Toulon Tournament and is thought to be keen on a move to the country for whom he has played all of his international football at youth level.
Swansea could be forced to pay around £500,000 in compensation for the forward, who came through the ranks at Coventry.
The Swans are likely to loan Thomas out to a Championship club next season should they secure his signature, rather than keeping him in their Under-23s.