Hi @AndreL22!
Can you please try to turn your question into a self-contained reproducible example? That’s the best way to help people here understand what you’re trying to do, and where you’re having trouble. To learn more, start here: FAQ: Tips for writing R-related questions
Gravtz/Graphtz isn’t a function in diagrammeR. Did you mean grViz? It would be a lot clearer if you could provide the code you used to get the diagram, as a starting point.