Truthfully it's got both, if you look at the underside of the rod puppet, it's got hooves covered by something resembling phalanges.
If you zoom in on the picture above, it is surprisingly obvious, I'm also sure other examples exist.
Such as on the various renditions.
You can see them clearly here.
Spoiler
So it does have hooves but the immutable Alien form overrides that and grows fingers/toes ontop of them anyway, the truth being in the films, the DNA reflex's just not as dramatic as lots believe.
No ridiculous bull horns for example.