Thankfully there are plenty of creative GF-bies out there who come up with all sorts of great recipes that are easily accessible [thank you 20th century, fast speed internet connections and the great world wide web!]. I found this graham cracker recipe at http://glutenfreegirl.com/gluten-free-graham-crackers/ and highly recommend it. It's easy, quick and delicious. The only thing I would recommend is to bake them a little longer than the website states if you are going with a thicker cracker - bake to a deep golden brown and you can't go wrong.
And, if you store them for a little while and they seem soft / stale - place them on a cookie sheet and pop back in the oven for a few minutes to get that crisp back!