I believe you will want to set your plot background to white, and then, simply add some interval markers to your configureChart extension function.
Example:
#def configureChart(self, chart):
from org.jfree.chart.plot import IntervalMarker
chart.plot.addRangeMarker(IntervalMarker(0, 15, system.gui.color(255, 182, 193, 155)))
chart.plot.addRangeMarker(IntervalMarker(25, 75, system.gui.color(144, 238, 144, 155)))
chart.plot.addRangeMarker(IntervalMarker(85, 100, system.gui.color(255, 182, 193, 155)))
Result: