SUMMARY:
Strategy Web 9.4.0 and later users are now able to minimize, maximize, hide and reposition legends in graph visualizations in Visual Insight.
Minimize and Maximize can be accessed by clicking on the new arrow displayed in the graph legend box as shown below:

Additionally the close button will now hide the legend from the visualization.
To re-position a graph legend, drag the legend box to the predefined positions as shown below:

WORKAROUND FOR PREVIOUS VERSIONS:
Visual Insight users in Strategy Web 9.3.0 and 9.3.1 have access to the maximize and minimize feature when using a graph matrix visualization as shown below:

However, users will not be able to re-position or hide legends. The available graph matrices are : Bar Graph Matrix, Line Graph Matrix, Bubble Graph Matrix and Scatter Graph Matrix.