For rearranging your diagram automatically with some distance between them you can try to use something like this:

let layout = new mxHierarchicalLayout(this.graph, mxConstants.DIRECTION_WEST);
layout.intraCellSpacing = 50; //horizontal
layout.interRankCellSpacing = 200; //vertical
layout.execute(this.parent);

The mxHierarchicalLayout method will automatically rearrange your current nodes. The other two settings will give spacing between them ( horizontally and vertically )

Also, run this before rendering the screen or if you want to change after the display has already rendered, just this.graph.refresh() if needed