Calendar: Changing the color of "all day events"

Hey all! I'm slowly begging to rely more and more on my calender (especially now that I have BIS sync it automatically w/ my Gmail account). I just have a quick question though. I input a lot of all-day events such as birthdays, corporate earnings announcements, etc. Also, my default calender view is "agenda view" because it's the most convenient for me. One problem though: if you look at the attached image, these all-day events are colored grey by default which is the exact same color as the dates. Apart from looking quite ugly, the lack of color contrast makes it somewhat harder to read (especially considering the fact that I like to quickly glance at my agenda as opposed to spending time going over it). Is there anyway I can change the color of all-day events?
Thanks in advance!