All settings for the FlowReactor editor are stored in a separate asset file. By default this file is located at the root of your project but you can move it wherever you want.
Access the settings either in your graph: Properties / Settings or in the Unity editor: Edit / Preferences
Here you can change the default node colors but you can also add your own custom colors for your custom nodes. Custom colors will be displayed in the node wizard.
Change all available shortcuts for the FlowReactor editor. Please note that each shortcut uses an additional CTRL key.