This is a rare and stunning image of Thethys because we don't usually see so many of the large craters althogether in such luminous relief.
The top one must be Odysseus. The bottom one might be Melanthius but that crater seems too far North. And the fainter big crater in the middle looks like Penelope. Please correct me if I'm wrong about these craters.
I've checked the maps and can't figure out any other interpretation. But then this could be because of the Sun-Tethys angle and similar to our own Moon this Cassini image could be a unique angle that throws shallower craters into greater relief.
But still, this is a most interesting image of Tethys. It says something to me that seeing even a familiar moon from just a few illumination angles is not enough for me to know it.