If you need a start with Dynamo, I recommend reading the Dynamo Primer and watching some tutorials. Afterwards, this thread should also be read: How to get help on the Dynamo forums, specifically point #7
Finally, one way to start the graph is to take all the floors, get the sketch lines/boundaries, use Group Curves from the archi-lab.net package, and then proceed from there.
Try out some stuff and then come back and let us know how it goes.