I too would be interested in how to do this. The <tt>-S</tt> option is not the correct one. I think you would need to edit the source of the extension to add
options['style'] = 'colorful';
However, I think you would also need to edit the <tt>maintenance/updateCSS.php</tt> script to also use that style, and run it, in order to update the CSS files in the <tt>modules/</tt> directory, as these are what define what the output actually looks like.
I tried all of that and although my colour scheme did change, it didn't come out looking correct. I wanted a dark style like a white-on-black terminal, but it persists in giving me a light grey background. Some further clues are missing.
For now I have switched to using the Highlightjs_Integration extension.