Julio Potier

This plugin adds 4 more colors into your admin/member profile. It changes the “4 squares preview” with a beautiful gradient preview. You can click on it to select the teme : it changes in real time to preview colors ! 
I added 4 icon themes for your admin menus, same behavior : click on it to preview.

BAW Better Admin Color Themes

Add more color themes and icons into your admin dashboard ! You can preview theme just clicking on it (JS required).

Cico Zeljko

wpvote

This is a simple plugin that will make your wp admin panel theme much more pleasant for work. Using specific colours you improve your work surrounding and simple and clean design of your wp admin panel.
<ul>
<li>30 color themes.</li>
<li>Tested with other popular plugins.</li>
<li>last update 8/5/2019</li>
</ul>
Video: 
https://www.youtube.com/watch?v=usB0PPeEczw

Colorize Admin

This is a simple plugin that will make your wp admin panel theme much more pleasant for work.

BAW Better Admin Color Themes vs Colorize Admin