The image below shows the dialog:
Edge Length
The preferred edge length between nodes.
Max execution time
An upper limit on the running time of the algorithm.
Node overlap
Whether overlap between nodes is allowed. If it is, a more compact diagram results.
Obey node sizes?
Takes into account node sizes during the layout procesure.
Number of iterations
The number of iterations of the algorithm, default =3.
Gravity factor
Regulates the tendency of the nodes to be placed near the barycenter of the resulting layout.
The greater the factor, the closer are the nodes to the barycenter. Negative values lead to huge layouts.
Layout start choice
Three choices are possible: