Not sure who the deity is--even Lama Zopa admitted in a teaching that he had not seen an picture of the deity, whom he didn't name, unfortunately. He did say:
"Another of the mantras is the Wish-granting Wheel mantra. I have read of the unbelievable benefits of reciting the mantra, but I have yet to see a picture of this deity. The mantra is very short: OM PEMO USHNISHA VIMALE HUM PHET. If you recite this mantra seven times every day, you will be born in a pure land when you die. And if you recite it and bless incense, whether stick or powder, by blowing on it, people are healed by smelling the burning incense. Here the healing comes through purifying the other sentient beings’ negative karma, through purifying their mind, which is the most important healing. Purifying the mind then helps to heal any sickness. If you recite this mantra and then blow on your clothes, wearing the clothes brings healing; wearing the clothes brings purification. And if the cloth is made of silk, wool, or the skin of an animal, reciting this mantra also helps that animal, no matter where it has been reborn, by purifying that animal’s negative karma."