Hmm, by coffee art, do you mean drawings on an actual cup of coffee or art drawn with coffee? 
I actually found both! Here you go:
Spoiler:
art in on coffee in a cup:
art done with coffee (an artist named Karen Eland uses expresso on watercolour paper to create her work):
I like my coffee strong. Please get me a cup of expresso (oh, I'd like a biscotti with it please
).