Develop visual relationship digram on Visio

Hello, I want to create an attractive visual on Visio to demonstrate some very complex relationships between different corporate groups. It is to visually provide an overview of how these groups relate to each other. For example, there will be about ten different groups that report to another committee or group. The list in the attached input file contains about 150 groups. Some groups report to multiple parties and other groups report to just one. There is a hierarchy wherein part of the first layer would look something similar to the attached (incomplete). What I require is a clear, perhaps colour coded, attractive visualisation of these relationships between the groups. I intend to print this in large A0 size poster, so please free to be creative. I will need all of the group names to be editable (those marked ABCD, XYZ etc). For the moment, in the attached input file, I have a column for Purpose. Each group should have a purpose, I am not sure how we can represent this in the Visio diagram, maybe in a collapsible box that can be expanded? I very much look forward to having someone creative who could work on this with me, as I am sure they may a few edits. I will need to complete this work by Monday 21st March so it is quite urgent. Thanks for your help