Greenaway’s film does indeed have a stunning color palette, and this is my personal interpretation of it.
I am sure there are more in-depth essays written on the subject, but as a starting point I would highlight Greenaway’s respect for, and interpretation of, European Art and his desire to make this film a living canvas.
If I recall correctly, the film starts with a scene of obscene violence against a naked victim and is swathed in blue hues. Blue is normally associated with calm or rebirth, but in this instance it is in direct opposition to the act being perpetrated. The kitchen scenes are bathed in green light, and this reflects the serenity of the environment – possibly the only stable area in the whole establishment.
I think the red hues of the restaurant are meant to reflect the abject nature of the scenes, and is closely associated with passion, death and violence – the themes of the film.
As for the clothes changing, you are spot on – but note that the Lover’s brown clothing doesn’t change according to the environments – he is bookish and dull and his clothing reflects this – he is unchanging (until the end of course).
Ultimately, this may be a simplistic take on what is a complex film, but I hope it is a good foundation for further answers.