To answer your questions as you asked them:
"So does this mean Jesus had a tattoo?"
Since the passage is undoubtedly talking about Jesus, and if you consider any sort of intentional marking on the skin to be a tattoo, then yes Rev 19:16 indicates that Jesus has/will have a tatoo.
"I thought one of the commandments was thy shall not graven image?"
The passage you're thinking of is this one:
Exodus 20:4 Thou shalt not make unto thee any graven image, or any likeness of any thing that is in heaven above, or that is in the earth beneath, or that is in the water under the earth.
Which doesn't seem applicable. I'm guessing you were really thinking of this one:
Leviticus 19:28 Ye shall not make any cuttings in your flesh for the dead, nor print any marks upon you: I am the Lord.
A good thing to understand about the Levitical law is that a lot of these laws were meant to keep Israel from doing the things of the surrounding nations. They were not a law of the heart.
Leviticus 18:3 After the doings of the land of Egypt, wherein ye dwelt, shall ye not do: and after the doings of the land of Canaan, whither I bring you, shall ye not do: neither shall ye walk in their ordinances.
These kinds of laws are usually referred to as Judicial/Civil law. The bible doesn't make this distinction, but we do because these were amoral laws that applied to the people of Israel because doing them would cause them to want to be like their surrounding nations. Having a tattoo, sowing two different kinds of grain, eating pork, etc... aren't inherently evil things like lying and murder. So assuming it doesn't cause a friend to stumble in their faith you and I can get a tattoo free of conscience.