Use a Color Expression node () to add coloring (according to an expression that you define) to the shapes or lines defined by a plot. You can add this subnode to the following plot types: Line Graph, Point Graph, Global, Nyquist, Arrow Volume, Arrow Surface, Arrow Line, Contour, Isosurface, Particle Trajectories, Streamline, Admittance Graph, Impedance Graph, Reflection Graph, Spot Diagram, Waterfall, Whirl.

In the Model Builder, add and define a plot group. Right-click the plot node (for example, Streamline) and select Color Expression.