Apache's mod_autoindex styling capabilities are heavily limited. This .php script tries to solve this. You can see it in action here.
Throw the .autoindex folder, .autoindex.php and .htaccess into the root of your webserver and you should be good to go. If you already have a .htaccess file, add its content to your existing one.
To change some default configurations and styles, use the .autoindex.cfg directory. It isn't available by default, so it won't be accidentally overwritten in case of an update. The example folder contains a sample config directory with further instructions.