To do this, you'll need to disable the !important flag where these colors are set in view.php. Look for line 24 and put /* css comments */ around !important, like so:
Then you'll be able to add something like this to your css:
.sf-submenu li a:hover {
color:#fff !important;}
Otherwise you'll have a hard time overriding the first link hover color. One thing to keep in mind is that your theme's styles may need to be adjusted so that it doesn't interfere with SF menu colors. That can happen sometimes if a theme is coded without much care for specificity.