Hello,
No there are no other options for out of the box styling. But you can edit it with CSS.
Here is the CSS for the active black background:
#s5_accordion_menu h3.s5_am_toggler.s5_am_open.s5_am_parent, #s5_accordion_menu h3.s5_am_toggler.s5_am_open.s5_am_not_parent {
background: #000000 none repeat scroll 0 0;
}
template.css line 482
You can add the following CSS to your custom.css file so that all the other items that aren't active have a background on them:
#s5_accordion_menu h3.s5_am_toggler {
background: #ccc !important;}