I don't know of any other graphing sites, but I have a suggestion.
If you don't want to completely graph it yourself, look for a cross stitch pattern for the team. They usually have them. Then just break all the numerous colors down to the major ones, for example, make all the red tones, one color of red, etc.
Use as much of the cross stitch pattern you want, figuring in a border around the cross stitch. Basically, one square is one stitch and a row of squares is one row of crochet.
To get the width and length of the afghan you want, I would find a afghan in the stitch (single crochet perhaps) you are going to use of that size and use it for seeing how many rows you want it to be and how many stitches across you want it to be. Or, you can do the math with your gauge.
I have found that single crochet makes a better graphing sitch as it is the same size up and down as across. Where as, double crochet is taller than it is wide.
Hopes this helps...