The PPV color contour and the PPV Legend will be visible after the PPV calculation on the seismographs is completed and if the vibration layer is set to visible.
To set the contour interval go to the Design Analysis menu.
Change the Contour Interval value to your needs.
There are four contour colors visible in the PPV Legend:
Green = 0 - Contour Interval Value
Yellow = Contour Interval Value -> 2X (Contour Interval Value)