how to style jquery Selectmenu component

how to style jquery Selectmenu component

Hello forum

I want to be able to style selectmenu as follows:

1) selectmenu will for example have 3 colors ( white, red and black) to choose from. 
2) If I select any of these colors, I want the color to show up on the selectmenu as a square, with the name specific to that color, for example:

if I choose white:




if I choose red:



if I choose black:



The full dropdown looks like this:





I was able to style it but I can't figure out h aving that color square show up, I'm new to jquery ui and I can't find anything on this specifically. 

Thank you