Changing color in grouped barplot in Matlab

You can use the 'FaceColor' property of the handles to the objects:

n=[46.4000   51.8000
   44.8000   44.9000
   67.2000   85.0000
   54.4000   60.3000
   43.2000   57.0000
   51.2000   68.0000
   75.2000   76.0000
   44.8000   51.3000
   67.2000   72.2000
   70.4000   71.2000];
bar_handle = bar(n,'grouped');
set(bar_handle(1),'FaceColor',[0,1,0])
set(bar_handle(2),'FaceColor',[1,1,0])

The documentation explains how to set the colors here.

For matlab2014b and higher

Using set doesn't seem to work anymore since matlab2014b and gives the Message (Error using subsindex: Function 'subsindex' is not defined for values of class 'matlab.graphics.chart.primitive.Bar'.).

Try it directly with the handle:

n=[46.4000   51.8000
44.8000   44.9000
67.2000   85.0000
54.4000   60.3000
43.2000   57.0000
51.2000   68.0000
75.2000   76.0000
44.8000   51.3000
67.2000   72.2000
70.4000   71.2000];

bar_handle = bar(n,'grouped');
bar_handle(1).FaceColor = 'r'
bar_handle(2).FaceColor = 'b'