Easel.ly - infographic creator that allows MULTIPLE editors. It is not super extensive on the free choices, but can be sufficient to get your information across and still be somewhat appealing to the eye.
Canva - infographic creator for one editor. While you could theoretically have multiple people logged into the same account, they wouldn't be able to work on it simultaneously. This, however, allows you to make much more appealing infographics and has many options for how to set them up. It does have some options to pay for items, but the free version works just fine.