It has been suggested that the new production insights charts & graphs could use some additional options for coloring the bars when grouping. Ideally any entity could be assigned a color (either by adding built-in color fields across the board, or implementing a feature like https://support.shotgunsoftware.com/hc/en-us/community/posts/209485148-Color-type-field), then there could be an option to leverage the color field to drive the bar colors when grouping by that entity in a graph.
Short of that, would be good to at least leverage the color field in this manner for entities where it currently exists already. This option exists currently for Status as a checkbox in the graph settings, so would be great to provide the same option for Task, Step, Project, Phase, and Department.
Another option would be to provide a color picker for groups in the graph, though this may be slightly less ideal because it wouldn't provide a way to use the same color consistently for the same entities (other than manually setting it that way each time).
Vote up this request to add your support for prioritizing this feature, and pass along any additional use cases or ideas in the comments.