Calendar how to change "Other Birthdays" color to match main

For years I've color coded Birthdays on my calendar software to be a solid Orange bar. After migrating data to Apple Contacts and Calendars, and using iCloud to perform the synch, I see "iCloud" calendars include Anniversary, Birthday, etc. The an Other set of Birthdays, US Holidays, etc.

I understand the Other Birthdays seems to rely on Contacts to obtain the data.

I can change the colors and even merge calendar items categories uner the iCloud calendar items. However, I do now know how to set the color of both Birthdays to matching Orange.