The ID number didn't work for me, but I found a different format using the username & team that does:
http://folding.extremeoverclocking.com/sigs/sigimage.php?un=HangThemHigh&t=36120&bg=1
The above is my username, if you didn't guess, substitute as needed. The bg=1 is the background - I tried 1 & 2, there may be more for different skins