Soooo
Since I no longer work there, I’m going to describe a well resourced project at a certain large company which has had rather little about it published.
But first Mind Maps, I think they are great for uncovering test cases , component interactions, user workflows and thus, good test-cases to go away and write up.
The Mind-Map technique is also an entire school of thought that uses graph permutation to design your test cases for you called Model Based Testing, this is a million miles away from Mind mapping. Model Based Testing is not something I know a lot about myself, mainly because I am wary of the expensive test heuristic after a bad experience using graph tooling based test design. I think MBT (Model Based Testing) has it’s place in any setting where you have either regulation as a constraint, or just have the resource available to you. Some MBT platforms use ML, another possible source of cost, but you can find a few good training or intro videos on how it works, and there are more than one or two commercial products that exist. Right here on the MOT 
Model-Based Testing "PetClinic" example using AltWalker and Python
But, I was going to tell you about a graphical test design tool from long ago. GTP (Graphical Test Planner) was such a tool. We had an architect create a directed graph language that supported flow charting of activities and branches in a uniform language (UML) using a popular vendors UML tool we were able to draw boxed representing workflow branches and environment differences and workflow start and end criteria. Basically GTP was a cool way of exploring user interactions with our system, but in a language that removed duplication, and was a fun way to document tests without having to write stupid numbered lists of steps, because the UML would easily capture decision branches. Our GTP language was so mature that we relied on it a lot, and were eventually able to travers the graphs to determine test coverage stats. Which is a brilliant goal achieved quite well in MBT tools. We even used colors in our graphs to represent various states, and made it possible to automatically mine this data, and if you really-really wanted to automatically change element colors.
GTP never was that silver bullet, I suppose it’s still in use there at that large company, but like so many tools, the things they do teach you have value. When they stop having value, you drop the tool. I believe that Mind Maps are like that too, they are like Marmite, good, but not with every single meal.