How to get list of files on Mac that have been tagged by Finder with a color?

I'd like to tag some files on my Mac with Finder under a certain color tag, and then be able to get that list of files using a Python or bash script. Is it possible to get the list of tags associated with a file via the command line or a Python script?

It's possible.

But you'll have to rely on xattr, xattr-lib should do the trick.
Some examples have already been made on how to use the xattr command line tool, those can be found here:

• https://apple.stackexchange.com/questions/110662/possible-to-tag-a-folder-via-terminal
• Get file's "get info" attributes in mac using python
• How can I add OS X "tags" to files programmatically?

I hope these help you out.
In worse case you could use a tool called tag:

tag -l file # list
tag -a tag1 file # add
tag -s red,blue file # set
tag -r \* file # remove all tags
tag -f green # find all files with the green tag
tag -f \* # find all files with tags
tag -m red * # match (print files in * that have the red tag)

This in combination with say subprocess.Popen could solve your needs.