No. The correct form is "your example was quite graphic". You'll find plenty of Google hits for "graphic example".
EDIT: Some years later, I find myself disagreeing with that "absolutist" No above. Here's an NGram showing that a graphical example has been gaining traction (whereas a graphic example has actually declined over recent decades, though it still accounts for the great majority of usages).
More to the point, this NGram shows that with the specific referent noun approach, the longer version a graphical approach is actually more common...

So realistically I'd have to say it's akin to electric/electrical, where the "extended" form is not generally used metaphorically in the way electric is. With no other context, I'd assume OP's quite graphic example was a somewhat metaphoric usage (giving clear and vividly explicit details), which could even be used in contexts with no visual component at all.
TLDR: For the literal sense (involving visual imagery, sometimes specifically charts or graphs), the -al form is more likely. For OP's "metaphoric" sense, the shorter form is much more common.