The correct answer is expression_3. This is a visualization of a procedure or the results of a procedure.
This is a visualization of k-means clustering, applied to our dataset.
If you say "visualization for," then you are indicating a destination or purpose of the vizualization, not what it is.
This is a visualization for my boss. He likes pretty pictures.
If you say "visualization about" then you are saying that the visualization doesn't really show the thing in question, but is somehow related to it as part of a description.
This is a visualization about the nature of these clusters. As you can see, k-means clustering clearly puts them into three groups.