There is a site called "Tree World," apparently part of a German wood products company that has some silhouette outlines of various trees.
The sugar maple is pictured here
A modified broom style bonsai would be nice. If you style the main branches upward in a meandering 45 degree angle and bring the laterals off that at angles approaching horizontal, you will have the general feel. Aim for an oval outline that is very characteristic of the sugar maple, and you will have a very natural looking tree. Add in a few younger short branches to fill in the base of the oval.
The site address is:
http://www.domtar.com/arbre/english/15.htm