To ensure fast loading, the RadEditor has been optimized in all possible ways and respects. One of the choices made when dealing with colors is to send just the values to reduce the array size by half (logic being that users will pick up a color on the basis of what they see rather than based on its name).
So, my suggestion would be to simply use the following syntax:
<color Value="LightBlue" />
If this is not a good enough solution for your scenario, you can use the attached sample page, which demonstrates how to override some methods of the color picker tool of the editor to allow for changing the string that appears in the color tooltips.
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