Create css file that hides menu like this:
.sf-menu{display:none;}
Save that file and link it in your page <head> with:
<LINK REL="stylesheet" TYPE="text/css"
MEDIA="print" HREF="urlofyourcssfilehere.css">
This will hide menu only when printing page.
MEDIA attribute is the key. Using it you can specify different css for each media: print, hendheld, etc.
See this link: http://www.w3.org/TR/CSS2/media.html