The colour scheme and layout of a Voice website is called the theme. Voice comes with a set of pre-created themes you can easily enable through the admin pages. Each theme has a range of options to change the colours, fonts, and layout.
The default theme is called Fresh, and is a good starting point for most sites, though you may want to change the colours to suite your group. If you want a completely different look then you can select a different theme.
From the admin pages, click the Look & Feel tab and select the Theme subtab.
This page lists all the themes available for your website, together with an Options button for each theme. Initially the Fresh theme will be selected.
If you want to keep the current theme but try some different colours with it, then click the Options button in the same row as the selected theme. Or click Select on a different theme to try that.
Changes to the selected theme or options are immediately applied to all pages in your website.
When I'm trying new themes I like to have two browser tabs open. In one I have the theme settings and in the other the website itself. Then when I change a theme option and click Apply, I skip to the other tab and click refresh to immediately see how it looks.