Visual management brings many things to mind when applied to lean manufacturing principles. We think of plastering charts, graphs, pictures, color coding, labels and work instructions all over our plant like wall paper. Just as in the case of work instructions, (see posting visual work instructions), this is just a partial truth. In the lean approach, visual management is more than just charts and pictures.
Based on what I was taught about the Toyota Production System, visual management is about seeing. Seeing the waste, seeing the problems, seeing the things needing improvement in addition to seeing the improvements from the eyes of the customer.
In American business, we have an extremely difficult challenge in seeing. We do not like to see problems and we overlook waste as just a cost of doing business. We get defensive when problems are brought to the attention of management (The higher up the organization, the more defensive). In the shuffle to deflect blame, we stumble through the improvement process hoping it will get better. Unwritten policies are followed like "never shut down the production lines" or "we need the parts now so write an UAI (Us As Is) disposition".
To move forward on your lean journey, you must first recognized this weakness in American business. Open your eyes in Gemba. You can not improve what you do not see.