Google-calendar – Is it possible to change the color of days in Google Calendar

In the web interface, on the left there's a list of your calendars. Each has an arrow that reveals a dropdown menu. In there, you can select a new color.

Note that this won't necessarily be reflected on other devices like iPhones.

Also note, where you see 'category' in Outloook, read 'calendar' in google calendar. it doesn't have the concept of categories. Just create a new calendar.

1. Go to Settings (Cog wheel on the upper-right side)
2. Search for Date format
   
3. Switch to 31/12/2012
4. Click Save at to the or bottom of the settings page