IPhone change calendar colors

sqlite3 should be installed by Cydia, or from command prompt:

apt-get install sqlite3

Query your current config:

cd /var/mobile/Library/Calendar
sqlite3 Calendar.sqlitedb

On the sqlite prompt:

select title,color_r,color_g,color_b from Calendar;

In my case the output is:

Default|-1|-1|-1
Birthdays|68|167|3
BreedveldCalendar|185|14|40
Calendar|246|79|0
Roland Breedveld|190|109|0

Change the colors, on the sqlite prompt:

update Calendar set color_r=47, color_g=141, color_b=0 where title = 'Birthdays';
update Calendar set color_r=181, color_g=0, color_b=13 where title = 'BreedveldCalendar';
update Calendar set color_r=103, color_g=10, color_b=108 where title = 'Calendar';
update Calendar set color_r=15, color_g=77, color_b=140 where title = 'Roland Breedveld';
.exit

RGB Values for the Standard Colors

Red = (181,0,13)
Orange = (229,98,0)
Green = (47,141,0)
Blue = (15,77,140)
Purple = (103,10,108)