Systems Thinking uses Diagramming to assist the process of analysis.
There are several key diagrams which inform the analyst about the problem. These are passed on the simplified analytical process of SUDA - Sensing, Understanding, Deciding and Acting. Diagramming is typically used in each phase as suggested below: -
Sensing the Problem
Spray diagram
Rich picture
Systems map (this can also be used in the understanding phase to make sense of the structure of the problems.
A Spray Diagram, my own work on a course project for my Institution.
Understanding the Problem
Systems map
Multiple cause diagram
Influence diagram
Sign graph
Systems Map, also of my Institution
An Influence Diagram
And finally, a Multiple Cause Diagram for one of my best OU students
Decision aids in solving the key parts of the problems
Multiple Criteria analysis (MCA) above See https://twentycc.squarespace.com/multiple-criteria-analysis/
SWOT and STEP analyses
Strengths, Weakness, Opportunities and Threats
Social, Technical, Economic & Political
The 4 Ws and an H: How, Why, What, When & Where?