Color a GeoJSON FeatureCollection so that bordering areas never have the same fill. Five colors are all you'll need.
install with npm:
$ npm install --save five-color-map
install with npm:
$ npm install -g five-color-map
then
$ fivecolormap data.geojson > colored-data.geojson
var fiveColorMap = require('five-color-map');
var coloredGeoJSON = fiveColorMap(geojson);
Each feature in coloredGeoJSON.features
now has a property fill
with one of five values:
At least one of your features must have less than 5 neighbors with adjacent sides. This won't work with a hexagonal grid.