Quadratic Discriminant Analysis Plotting All Class Boundaries

Hi all, I'm looking at quadratic discriminant analysis for data classification. I based it on the example that is available on the mathworks website: Here

I've been able to draw the class boundaries between all of the classes except one, see the attached picture below. I'm trying to draw the class boundary around the orange class (similar to that drawn round the blue class), can this be done?

Thanks