She will grow out of it, I promise. It's just one of those lovely phases they go through! Keep telling yourself that to her, it's just a game. She is too young to understand she is upsetting you. You're a nice easy person to try it out on, that's all.
DD1 was a big hitter. One thing I did used to do was put her down and walk away when she hit me, just for a minute. By withdrawing attention for it, she go to understand that it wasn't what we wanted. Get your DH to back you up. If he picks her up and she lashes out at you, just get him to say, "no hitting," in a matter of fact tone and put her down.
If it makes you feel better, DD1 used to hit me so much that my friends used to prophesise she would grow up violent, have problems at school, all sorts. None of those things happened. She is now 16, is absolutely lovely, has been the easiest child to get through the school years - and we have a very close bond.
It doesn't mean anything, but I would try to break the habit in a kind but firm way.