They are not going to show talis face, nor any quarians, they are too frightened.
But if you really want to know, before they chickened (because every one has his own dreams for her face, good or bad), there is a final artwork for her body in the art of Mass Effect, that body was the version that they used for ME1, and that one had the face drawn, a normal human face (so im pretty sure thats the face they wanted to use when she was romanceble in the first game). They have also described the quarian face in the books as something similar to humans.
And well, you can see clearly her human face if you look in her visor (ME2's pc mod of high quality texture has an option of a less opaque visor).
The Tali I most like form one of the fan artist, is the famous one were she has a very human face and looks really nice, and resembles the original artwork (although he added hair). I know some people want something that resembles and insect or some shit like that, but I prefer the "artwork/fanart/what you can see under her visor" version, than you.