You only use three colors, so you can change caxis value in order to have the values you want at the limit because the colors, knowing that it will create 3 equal length colors. Then change the limits of the axe. So you can add to your code:
limitGreenYellow = 9.5;
limitYellowRed = 40.5;
caxis([2*limitGreenYellow-limitYellowRed, 2*limitYellowRed-limitGreenYellow]) %limits of the color bar
c=colorbar; % show color bar
xlim(c,[min(limitValues),max(limitValues)]);
Another (better?) way to get what you want would be to have a huge colormap, 1 row for every integer, and it would work for more than 3 colors:
limits = [0,9,10,40,41,50];
colormap([repmat([0 1 0],limits(2)-limits(1)+1,1); repmat([1 1 0],limits(4)-limits(3)+1,1); repmat([1 0 0],limits(6)-limits(5)+1,1)]);
caxis([0, 50]) %limits of the color bar
