The Yerkes-Dodson law is graphically represented by a line graph where performance quality is plotted on the vertical axis and arousal level is plotted on the horizontal axis, with both axes showing a range from low to high. The graph contains two inverted U-shaped curves representing task performance: one for difficult tasks and another for easy tasks. This visualization illustrates that optimal performance for easy tasks is achieved at a slightly higher level of arousal compared to difficult tasks.