Graph Formatter is an Unreal Engine plugin that can arrange graph nodes automatically.
Clone or download this repository to the "[root of your project]/Plugins/GraphFormatter" and restart UE4 Editor.
https://www.unrealengine.com/marketplace/graph-formatter
Select nodes you want to arrange, or just deselect all nodes and press "Format Graph" button on the toolbar.
Configure it in "Editor Preferences/Plugins/Graph Formatter".
It is based on the ideas of Layered graph drawing.
References: