The allocations graph (Projects > Allocations) provides you a comprehensive visual view about the resourcing situation for your projects.

The legend in the left side of the graph explains every color and what that color represents. By clicking on any of the rows in the legend you can hide it from the graph. You can enable it by clicking again.

Like most of the graphs found in Silverbucket the view mode and allocation units can be changed from the top-right corner of the graph.