Hello...me again.
Silverstripe works on the basis that the developer styles the design of fonts etc in the .css files. You would therefore set the colours for your <p> and H1->H6 tags etc in the typography.css file. We don't really encourage changing font colours on the fly, because you might have a lovely design and then a content editor messes it up by using some awful coloured text. You will also notice that unlike other CMS's you cant change the font faces in the CMS either...for the same reason.
That being said, if it is critical to the design of your site that users be able to do that...you can extend the TINMCE interface to allow making changes to fonts and colours...this hower will require some coding.
Go to your _config.php file and add the following code:
// Enable text colour in the CMS
HtmlEditorConfig::get('cms')->insertButtonsAfter('strikethrough', 'forecolor');
here is a article on it:
http://www.ssbits.com/tutorials/2009/customising-the-wysywig-editor-in-v2-3-2-tinymce/