Create a multicolored line with markers at each vertex. Interpolate the colors and use a colorbar to show how the values map to the colormap.

Create the data. Set the last entry of y to NaN so that patch creates a line instead of a closed polygon. Define a color for each vertex using the y values. The values in c map to colors in the colormap.

Create the line. Show markers at each vertex and set the EdgeColor to 'interp' to interpolate the colors between vertices. Add a colorbar.