I live in Spain and I haven't been to many mcdonalds restaurants but I don't remember there being any music at all? Just loud chatter. But people here are generally loud so perhaps they simply didn't think it was a good idea to have music.

I don't know much about how they looked in the past but currently they have sober colours. This is what a current restaurant looks like: https://s3-media0.fl.yelpcdn.com/bphoto/RxMy6l6HjBZujf7pHjtR... Seems like mostly hamburger colours? Mustard, lettuce, tomato.