There is a petri net tools database at https://www.informatik.uni-hamburg.de/TGI/PetriNets/tools/db/cpnami.html although the link for the GUI Macao tool is broken.
I have used various GraphVis based tools for this in the past https://graphviz.gitlab.io/resources/ though I have not found one to date that is really simple to use.
Generally seems that the dot format is used for petri nets, this requires coding the network as a dot file in a text editor and use various tools to render it. https://en.wikipedia.org/wiki/DOT_(graph_description_language)
Hope that helps.