Being able to choose a different color for each tag would make it much easier & more efficient to (1) find the tag you're looking for from the list on the sidebar & (2) find any bookmarks with a certain tag from a collection.
I know you can just use the tag in the search bar to filter the collection, but sometimes I want to still be able to view the whole collection simultaneously. Plus it's just slower to have to type in the search and wait for it to load, and then maybe go back to the whole collection if I didn't find what I was looking for.