changing colours of the data points in a biplot

Suppose I have:

A = rand(100,5);
[coefs,score] = pca(A);
biplot(coefs(:,1:2),'Scores',score(:,1:2),'VarLabels',vbls);

There is a default size and colour of the data points that appear on the biplot.

I want to customise my own to show different aspects of my data. For example: I want the first 20 points to be green coloured, second 20, to be red, etc etc. How do I this?

[Adam]

You can use the

hPlots = biplot(coefs(:,1:2),'Scores',score(:,1:2),'VarLabels',vbls);

syntax to return the plot handles, although you get literally one handle per point on the graph so you get a large number of them that you would have to fish through and set the colours on. You can set lots of colours at a time with e.g.

set( hPlots, 'Color', 'b' )

or whatever, but you need to index only those plots you want and remove the various other lines and bits and bobs from your array of handles.

[Heidi Hirsh]

Can someone elaborate on how to do the indexing to select a subset of the points? I've tried doing so and the data plots in different locations if I select a subset.