I get a warning that KaleidaGraph is not optimized for my Mac. Is there a 64-bit version of the software?

Yes. Version 5 of KaleidaGraph is a 64-bit version that will run on Mac OS 10.14 (Mojave) and later and supports the M1-M3 chips.

Note for OS 10.13 users: Version 5 will run under OS 10.13 (High Sierra) but you may get an error that the app is damaged due to a problem related to GateKeeper. You can get around the issue by opening Terminal and running the following command:

xattr -cr /Applications/KaleidaGraph™\ 5.0/KaleidaGraph.app

This will remove some of the attributes of the application and allow it to run.