One of the artists featured in Masters of the Poster, which I discussed earlier in connection with absinthe advertising, is Pierre Bonnard. Here's his poster for the Revue Blanche.
Bonnard (1867-1947)was a major painter and graphic artist, who did a lot of book illustrations before going on to become one of the major Impressionists.
A novel I came across recently is Guy Goffette's Forever Nude (or, in the original French, the slightly less Swedish-naturist-resort-sounding Elle, par bonheur, et toujours nue, which I think translates to something like 'She, Happily and Always Naked'). It's a novel about Bonnard and the woman who became his wife and the model for his many nude paintings, Marthe de Meligny.
Here's the cover of the English version, and an excellent Penguin Guy de Maupassant story collection that uses the same image.
It's called 'Red Suspenders' in English, and I can find find very little about that particular painting, other than the fact that it is indeed a portrait of Marthe.
Here's the original French cover, with a nude painting of Marthe.
Here are several more lovely Bonnard Marthe nudes, and a rather funky early photograph of her which I think would also make a compelling cover image for this novel.