So, for the variant tiefling rules that give them different stats depending on what kind of fiend they are descended from, I'm wondering how said tieflings would look different. I was thinking the Motherless (Qlippoth born) might have tentacle-like things in place of horns, (though said tentacles couldn't attack or wield anything). I was also thinking some of the Hungerseed (Oni born) and Beastbrood (Rakshasa born) tieflings might be human-passing (as the oni and rakshasa like to disguise themselves as humanoids,) but would still have something odd about them (such as really intense, predator like eyes.)
There is an article by James J. Haeck that has pictures of the different versions of Tiefling...
I used Google and searched Images for Pathfinder Motherless Tiefling, and there were literally pictures of the different versions.
The "Blood of Fiends" book has art for each of the heritage. Qlippoth look horrifying, for instance. The Oni and Rakshasa are my favorites
The only missing ones, if they even exist, are Sakhil-blooded and Dorvae-bloodled tieflings.