Select File - Export Current Model - Errors - Colour STL File to display the Save Errors dialog box, which you can use to save the current shaded triangle error map as a colour STL file.
This is the standard Windows™ Save As dialog box. For further information about how to use it, click on the
button on its Title bar, and click on the area you are interested in.
You can then import the file into any application that supports STL files.