You may be right. I guessed it may have Sphinx, but not sure about the long mane. Could have some Maine-Coon in it. I have a grey Maine-Coon and they are stocky in the back end like this one is. Although sort of hard to tell for sure without being able to see the tale-tale markings of the solid color stripe down the middle of the back, the bobcat type tufts of hair on the ears.
Whatever the breed/breeds of this cat is, it sure is a piculiar creature.