The way to change the color, background color for links, hover links, etc., is with CSS. This is the standard CSS that come with Indexhibit (it uses your browser default for coloring - which is typically blue):
a:link { text-decoration: none; }
a:active { text-decoration: none; }
a:visited { text-decoration: none; color: #666; }
a:hover { text-decoration: underline; }
You can find your CSS rules in the /ndxz-studio/site/$template/style.css file. In the Settings section of Indexhibit you choose your template set. It is advised that if you are altering your styles that you use the "Sample" template set or create your own set.
Without an exhaustive explanation (you can search on Google for css and links if you need that)...you can change the color of text, background color and basic link attributes. This example changes the links to red, has a yellow background when the mouse is over the link and turns the link to a grey if it has been previous visited:
a:link { text-decoration: none; color: #f00; }
a:active { text-decoration: none; }
a:visited { text-decoration: none; color: #666; }
a:hover { text-decoration: none; color: #f00; background: #fff20d; }
If you use any background colors in your links it is advised that you add these rules so that your images should not have the odd background colors as well:
#img-container span.backgrounded a,
#img-container a.thickbox,
#img-container a.thumb-img,
#img-container #d-col1 a { background: transparent; }
This html is a list of basic hex values for colors.