I guess there isn't an answer to this:

Using Win XP and Outlook 2007 and shared calendars on our Exchange Server

Each person involved has created a second calendar (not their primary
calendar) with information that is to be shared with other staff. Those
calendars use categories whose colors have been renamed to reflect the
user's individual needs.

For example, one person is the keeper of the school athletic schedule, and
he has renamed his color categories to reflect "home games" and "away games"
and "varsity practice" and "junior varsity practice."

Another person is the keeper of staff vacation times, and she has renamed
her color categories to reflect "staff vacation" and "management vacation"
and "office closed."

These calendars have been shared with everyone in our group.

When I view one of the calendars, I see the various colors and when I click
on the category button, I see the assigned category names. When I view one
of the other calendars, I do NOT see the various colors and when I click on
the category button, all I see are the color names (red, blue, yellow)
instead of the assigned category names.

Does anyone know what might be causing the difference???