Prepositions are hard to teach, especially if the context is limited to one sentence. But all three prepositions could be used. And it does not matter if the movie has original music and/or pre-existing music; the general uses of the prepositions are the same.
1) I like the music in the movie Ray.
I like the music featured in, found in, contained in, heard in, played in, etc. the movie Ray.
2) I like the music from the movie Ray. That is why I bought the OMPST (official motion picture soundtrack) on CD. I can listen to music from the movie whenever I want.
So music from the movie means the music that comes from the movie.
3) I like the music of the movie Ray.
This is a general statement. It is like saying:
I like the movie Ray's music. Or: I like the movie's music.
You can also say:
4) I like the music of Beethoven (= Beethoven's music) in the movie Ray.
5) I like the music of Beethoven (= Beethoven's music) from the movie Ray.
But you would probably not hear the above sentence with two of's in it.
You could also say:
6) I like the music of movies that have Beethoven's "Moonlight Sonata" in them.
7) I like Beethoven's "Moonlight Sonata" in the movie Ray, but I don't like any of the other music in, from, or of the movie.
Edit: It should be clear that it doesn't matter if the music is "original music" or not.
8) The music in / from / of Forrest Gump includes all the songs I used to listen to on the radio.
The music of Pulp Fiction
also mentions The music of Guardians of the Galaxy.
There's the Blog of Doug Adams, which is called The Music of The Lord of the Rings Films
. Or The music of American Horror Story: Freak Show
. Mobile link
. Or you can buy The Music of Star Wars
or The Music of Grand Theft Auto
if you search for them.