It would be helpful, if a developer who uses javafx.scene.paint.Color could see the actual color in the JavaDoc instead of just "The color alice blue with an RGB value of #F0F8FF."

This is just a convenience feature, to avoid looking up the hex code somewhere else.

I suggest putting something like this in the JavaDoc:
<div style="width:50px;height:50px;background-color:#F0F8FF"/>

in order to show a small rectangle with the according to color.

Or you could just style the background-color of the text accordingly.