You can layout your diagrams automatically by choosing the corresponding context menu items from the diagram context menu. This settings panel lets you specify which direction the layout algorithm should take by default for the alignment.
The vertical layout will align all your diagram elements from top to bottom, beginning with the most specialized class, then the more generalized ones further to the bottom.
Instead, choosing a horizontal layout will organize your elements from left to right, starting with the most derived classes on the left.
UMLBoard uses the ELK Layered layout algorithm with an orthogonal routing style based on an implementation of Sugiyama, Tagawa, and Toda.
Support for other layout algorithms and additional parameter options is planned for future releases.