Script Download: ImportOSCEXOMasterCategoryList.zip
http://gallery.technet.microsoft.com/scriptcenter/Import-Category-List-for-2ef1bc05/

This script demonstrates how to import master category list for multiple users in Office 365 Exchange Online. This script requires you to add proper permission to the default Calendar folder before exporting or importing master category list by default. However, this script also allows you to use Impersonation. Impersonation enables an account on an Exchange server to perform actions by using the permissions that are associated with another account.

Currently, Outlook Web App (OWA) does not allow you to export or import master category list (color categories). But some of you rely on this feature for handling your email messages efficiently. For example, you want to import a master category template list for new hires. So you want a script to mitigate this issue. 

image image
image

You can find more All-In-One Script Framework script samples at http://aka.ms/onescriptingallery