Actually since this is part of Unity, the code for a graph like this may already be built in. A quick google search found me this: https://docs.unity3d.com/ScriptReference/EditorGUI.CurveField.html

Better yet, just allow me to optionally create a second Main Node within the same shader graph area, with all the same inputs as the main, Main Node. Only this... main node... will be called the Shadow Pass Main Node, or whatever. The rest is pretty self explanatory.

Or is it self explanatory? If it isn't self explanatory I'd be fine to explain it all right here. Lets see, two Main Nodes, but one of them is called Shadow Pass Main Node. The shadow pass main node has all the same inputs (21 of them? Can't remember). Can hook up all the stuff you want to happen in the shadow pass, which might be substantially less than what you need for the main pass. This is all for optimization of course.

HMMM and ooh, this would be tasty... if you select the shadow pass main node, then the menu on the left would say "shadow pass", and all the options there would be changed to show what you can do in the shadow pass.

HMMMM and ooooh, why not just let me add as many main nodes as I wanna, so I can make as many passes as I wanna. Mmmm.