Just perform Pearson or Spearman correlation depending on your data. Then display the resulting matrix as an image and apply any colormap of your choice.
%% Code Snippet
corr(yourvariables)
imagesc(ans); % Display correlation matrix as an image
set(gca, 'XTick', 1:sizeofyourcorrmatrix); % center x-axis ticks on bins
set(gca, 'YTick', 1:nsizeofyourcorrmatrix); % center y-axis ticks on bins
set(gca, 'XTickLabel', yourlabelnames); % set x-axis labels
set(gca, 'YTickLabel', yourlabelnames); % set y-axis labels
title('Your Title', 'FontSize', 10); % set title
colormap('jet'); % Choose jet or any other color scheme
colorbar on; %
