Why yes, you can.
You need to be subscribed to the Color Schedule calendar in Google (see more). You can hide and show calendars by clicking on their names in the left-hand sidebar (I leave the Color Schedule hidden most of the time, because I find it overwhelming).
- Turn on the Color Schedule calendar and find the block you’re looking for (Wednesday Blue, for example).
- Click on the block (not the name — that will take you to a less useful detail view) in the calendar.
- Click the “copy to my calendar” link in the balloon that appears.
- Edit and save the event that is now both at the right time and the same color as the block you copied!