I don't know what the author of this article, used but the current iteration of Vexlio [1] is a good fit for this type of diagram. (I am the developer). [1] -

I don't know what the author of this article, used but the current iteration of Vexlio [1] is a good fit for this type of diagram. (I am the developer). [1] - https://vexlio.com https://vexlio.com