Vaguely orange. I wouldn’t want someone to think it was going to taste like actual oranges. They used to joke that the main ingredient was iron girders, but that advert was banned in the US for “false advertising”
The original recipe Irn Bru is also banned from the US as it uses a non-standard colouring. Some Scottish people will tell you it was a move by Coke to specificlaly stop Irn Bru being sold, but I’m not convinced Coke really care about it all that much.
Apparently there is now a US compatible variant recipe with a different orange colouring but all comments I’ve found suggested it tastes quite different.