The organic layout algorithm is usually the best choice for these kind of structures. However, while running organic layout may improve the distances between nodes, the algorithm will not necessarily produce a circle like in your illustration unless you specify an elliptical output restriction (see tab "Area Restrictions" in the organic layout settings).
A good approach might be running the algorithm without an output restriction, note down the bounds of the resulting layout, and then run the algorithm again with an elliptical output restriction that is inside the previously noted bounds.
