It looks like it can be deciphered. If you know how to use Inspect Element, look at the a class. You can see where they have colored the border, and the icon by denoting them as specific children using (2n), (3n), and so on. You will see the color they used on the element. You can play around in inspect element without doing any harm. Try changing the color, and watch the affect. Once you know you have the right one copy it into notepad, and paste it into your custom css in the admin panel for the theme. It will take a little work since they use so many different colors, but once you have the elements you need, the rest is just changing the child specific denotion in the element.

P.S. Don't forget about the hover color, and the "!important".

Here are a couple of examples of how I implemented font awesome icons in the menu.

.groups_main_menu_list a::before{
   content:"\f0c0"!important;
}
.event_main_menu_item a::before{
   content:"\f073"!important;
}

Thanks. Ill give it a try and let you know how it goes.