The only way I can come up with is to make three separate charts.
It's not too hard either
Here is the table I used:
The first row and column are headers
select the first row of data (cells B2 thru G2)
now add a bar chart from the Charts menu
Format as needed
hold the option key then click and hold on the chart, then drag (this will duplicate the chart)
Now click the "Edit Data References" button below the chart
click in the blue, shaded region of the table and drag down one row
repeat for the last series
now you can click the chart and then any of the colored bar and use the Style Formatter for the selected series to change the color and shading type: