https://en.wikipedia.org/wiki/Venus_de_Milo
http://www.louvre.fr/en/oeuvre-notices/aphrodite-known-venus...
http://penelope.uchicago.edu/~grout/encyclopaedia_romana/mis...
http://www.enotes.com/homework-help/why-aphrodite-milos-bett...
If you really have to be pedantic, say the Aphrodite of Milos, since this is a Greek statue.
I assume the name is probably French, because it was discovered by a French archaeologist. I think it could also be Latin, since I think "Milo" would be the dative case of "Milos", but I'm not 100% sure (I haven't read much Latin since leaving university).
In either case, Spanish has nothing to do with the matter, the name is perfectly valid, and more generally "Venus de Milo" is the canonical name. I'm sorry if you don't like that, but there's no way in which it is is less valid than using an Italian name in English conversation.
Also, you probably wouldn't say "Venus of Milo", because that's a really awkward way to refer to the geographical origin of something in English.
Edit: As sister posts point out, the french meaning is far more appropriate, but the latin is valid as a root.
http://penelope.uchicago.edu/~grout/encyclopaedia_romana/mis...