My Blogroll isnt showing categories

The layout I just started using doesn’t separate my links into categories. Here is the code for the blogroll, will someone please change it so it will separate the links into categories?

<li id="Blogroll">
	<h2>Links</h2>
		<ul>
			<?php get_links(-1, '<li>', '</li>', ' - '); ?>
		</ul>
	</li>