1. Load or generate a Raster data set into a Map window
  2. Find the Raster data set you want to customize in the Layers list and select it.
  3. Right click it and select Options.

  4. Select the desired Display type (e.g. Gradient or Palette)
  5. Customize the display options as desired. 
  6. Click OK to see the updated raster display.

Example Gradient customization:

Example Palette customization:

Example Palette raster display: