text: PROC POWER: Linking Plot Features to Analysis Parameters :: SAS/STAT(R) 9.3 User's Guide
  Suppose you supplement the sample size analysis in Output 70.8.5 to include three values of alpha, by using the following statements:
  The defaults for the VARY option in the PLOT statement specify line style varying by the ALPHA= parameter, plotting symbol varying by the GROUPMEANS= parameter, panel varying by the STDDEV= parameter, and color remaining constant. The resulting plot, consisting of two panels, is shown in Output 70.8.14.
  Output 70.8.14 Plot with Default VARY Settings
  Suppose you want to produce a plot with only one panel that varies color in addition to line style and plotting symbol. Include the LINESTYLE, SYMBOL, and COLOR keywords in the VARY option in the PLOT statement, as follows, to produce the plot in Output 70.8.15:
  Output 70.8.15 Plot with Varying Color Instead of Panel
  Finally, suppose you want to specify which features are used and which analysis parameters they are linked to. The following PLOT statement produces a two-panel plot (shown in Output 70.8.16) in which line style varies by standard deviation, plotting symbol varies by both alpha and sides, and panel varies by means: