If you open the "Print" dialogue box and then the "Page Set Up" dialogue box, check that "Color / Gray Scale" is selected, ok any changes you have made. Your drawings will now print in full colour.
Thanks Tim for advising that it works for you.
I looked further into the dialogs and found two different paths for printing drawings:
1) File>Print>Properties>Select color: Auto color OR Grey scale>Print
Auto color prints all black.
2) File>Print>Page setup>Drawing color: Automatic OR Color/Grey scale OR B&W>Print
Color/Grey scale prints color in color.
Quirky, but this is SW.