Where are the iCloud Drive icons located?
I think you are looking for either of the following files:

/System/Library/PreferencePanes/iCloudPref.prefPane/Contents/Resources/iCloud.icns




/System/Library/CoreServices/Finder/Contents/Resources/iCloudNoDocs@2x.png


Without clarification I can only guess what you want but I think I figured out that you want the folder icons shown within iCloud Drive. It seems like those icons are just a generic folder icon with the relevant app icon superimposed on top of it.