According to producer David Heyman, Graves does not appear in the movie and there are no plans for him to appear in future movies either.
SnitchSeeker: Is there a real Graves? what happened to him?
David Heyman: That's a very good questions. I've been wondering ... I'm amazed more people haven't picked up on that. Yes, there was a real Graves. Yes, someone used some polyjuice potion and took their place. I don't know where they are at the story's end, But yes, there was a real Graves. We didn't film him. We didn't film the polyjuice. We just dived into the story midway through.
SnitchSeeker: Will we see Graves in the future?
David Heyman: I doubt it.
SnitchSeeker: It is similar to what happened with Crouch and Moody in the fourth book.
David Heyman: Yes.
SnitchSeeker: I guess Colin Farrell won't be back in the sequel.
David Heyman: There's no plans to bring Colin back for the sequel.
David Heyman talks to SnitchSeeker about the real Graves & his fate in 'Fantastic Beasts
Note that J.K. Rowling later clarified that the transformation wasn't actually done via polyjuice.
Why did ‘revelio’ undo the effects of Polyjuice Potion?
It didn’t. Grindelwald’s Transfiguration surpasses that of most wizards, so he used a spell, not a potion, to take on the appearance of Percival Graves.
J.K. Rowling's new website - FAQ