Two more diagrams would be needed to show a complete cycle, but it's fairly easy to understand what's happening.  A&D always move in the same direction in a square, movin from corner to corner after each pass.  B&C do the same in their own square.  Passes are made alternately to each of the two passers in the opposite square.  In a version that may be easier, passes may always be made to the same person if A&D rotate in the opposite direction.
The rhythm is usually a 4-count.

For a 6 jugglers version, try prism.

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