This 7-zip theme manager offers 60 toolbar themes and 15 file type themes and only requires a single click to activate the theme.
Download the 7-zip theme manager from here (5.74Mb) and extract it. Run the program by clicking on 7zTM icon. No installation required. It automatically (or manual) find the 7-Zip installation folder.
Then select a desired theme and click ‘Activate theme’. All 7-zip archive file icon on your computer will changed into the new icon.