Several British university libraries have organized audits, and you can start with a pre-existing tool.
You can also generate your own audit categories. How do the authors you assign vary by:
National origin
Current location
Theoretical perspective
Race
Gender
Age
And......
Some questions to consider:
What is the relevance of the author’s identity in this context?
Who is talking about whose experience and/or culture?
What kinds of sources do we perceive to be of most academic value and why?
What other questions would be worth considering when analyzing your reading list?