Laying the nodes out
There are some useful buttons available in the PIVOT DIAGRAM | Layout ribbon group. The actions apply to the immediate child nodes of the selected Pivot Node shape or shapes. So, in the next screenshot, the child nodes are shown with the Alignment | Left option, but they are about to be changed to Alignment | Top. This will cause them to rearrange vertically:
The direction of all the child nodes of a selected Pivot Node shape can also be changed, as shown in the next screenshot where the whole diagram was changed from Top-to-Bottom to Left-to-Right: