I don't know any site for making infographic but I tried to search some and found out a lot of them. While you still don't have a free infographic maker website yet why don't you try to use those free websites that claims to be free? Just try to make a simple infographic and see if you can publish and download it for free. You're lucky if you found one.

Anyway, if you're about to make an infographic with that design, I think using Photoshop is fine and enough.