After reading the posts at this link: Change LVOOP Class Icon Color on All Members I wrote a small project provider that allows the user to recolour the small box created by default for a new class.
This can be useful when you change the banner colour, but are still left with a box of the old colour.
The 2017 version is tested, the 2013 version I have not used (it is created only by backsaving).
At present, you can only use this on one class at a time, but it should be fairly easy to modify to have the tool work for multiple selections (I just don't anticipate needing that immediately).
Right click on the private data control to use the tool. The ellipses version brings up a dialog box.
Colour can be changed to Color using the string constants in the "..._Item_OnPopupMenu.vi".
Edit: removed the files and added new versions.
Updated to add a cancellation button and prevent hanging when closing the window opened by the ellipses menu item via the X in the upper right corner. Now that will also cancel the operation. Improved default colour choosing in the dialog (matches the behaviour of the non-dialog version now for its default colour) and gave the window a more appropriate title.
As before, the 2013 version is backsaved and untested. Only the 2017 version is tested.