First you need to create the text that you want to link.

Using the 'insert web link' icon on the right, add the link to your text

Your text now has the link applied, and as you can see, has defaulted to blue

Select the HTML tab at the bottom of the editor window to see the email code

Navigate through the code to the link you have just added

Add a font tag inside your link tag, surrounding your text, and set the colour you would like the link to be using a 6-digit HEX value.

An example tag would look like:

<font color="#000000">Find out more</font>

In this example the link would turn black, as #000000 is the HEX colour value for black.

Make sure you have an open and close font tag

Click the DESIGN tab at the bottom of the window to switch back to design view

You will see that your link is now the colour you set in the HTML code