It is possible to over ride the standard colour schemes set for the bar chart with theming that will change the colour of the chart depending on the value.
There are 3 modes for the theming; Plotted Value, Range and Specific Value
The plotted value selection will take the value that is being plotted as the X axis value and check to see what range this value fits in, then plot the colour depending on where this value sits within the ranges.
In the example above, there are a set number of ranges with colours to match. If the value on the X value fits within one of these values then it will plot as that colour.
The Range selection will take a value from a specific field and then apply the same logic as the Plotted Value selection above.
In the example above, this takes the N value field and will colour the bar on the chart depending on how high the N value is.
The specific value selection will take a value from a specific field and then colour the bar on the chart that colour.
In the example above, this will colour the chart green if the SPT test was a S test, where as it will colour the bar Red if it was a C test.