While there's no photo for this one (all the machines running the next-gen games were hidden away in little wooden prisons, shielded from the prying eyes of public and journalist alike), I did see an actual PS4 debug machine at one point. But while a sneaky, clandestine, anonymous viewing of said machine would have allowed the opportunity for furtive snapping, in this case the machine was quite openly (but very unofficially) shown to me when I was chatting to a dev after a game demo.
Thus, ironically, the ease with which I saw it actually made it impossible to get a pic, lest I drop said dev in a huge great pit of poop. For the record, the debug machine looked a bit like a small, chunky-but-sleek black PC. It was quite pretty.