In ChartDirector you can set different zones of the chart as different colours depending on the data values:
c.angularAxis().addZone(4.5, 5.5, 0xffff00)
c.angularAxis().addZone(7.5, 8.5, 0xffff00)
However I cannot find any equivalent for plotly. I have been searching through the chart attributes (https://plot.ly/python/reference/) and nothing appears to do the equivalent. Is this possible within Plotly?
You might also want to look into Gauge Charters, and see if they might work for you. Some hacking/modifications may be necessary however.