An embodiment provides a timeline upon which a playhead indicator is moved or positioned. Changes to a displayed graph that are within a predetermined interval of the playhead indicator's time position are shown graphically on or near the graph. Actor icons are positioned on or near the displayed graph. The actor icons correspond to different entities (e.g., a person, group, organization, software agent, etc.) that has made a change to the graph. Action beams are displayed to show changes to the graph. As playback of the change events occurs, beams emanate from actor icons to items in the graph that are changed or otherwise operated upon. Various characteristics of the beams' use, appearance and behavior are described.