One type of display is a frequency distribution curve.
This is a graph you are probably used to seeing, and often takes the form of a bar graph.
The length of each bar indicates either the frequency or number of students within a certain salary range. It helps to get an idea of the most typical salaries students are earning in their first year.
This display is more appropriate than, say, a line graph, because the graph is not supposed to show change over time, but just a snapshot of students' salaries after graduating.