var viewer = new Cesium.Viewer(‘cesiumContainer’);
var scene = viewer.scene;
var model;
var hpr = new Cesium.HeadingPitchRoll(0, 0, 0);
var origin = Cesium.Cartesian3.fromDegrees(-123.0744619, 44.0503706, 0);
var modelMatrix = Cesium.Transforms.headingPitchRollToFixedFrame(origin, hpr);
Make sure you’re using the latest version of Cesium. Model coloring was added fairly recently. You can get the latest download here: http://cesiumjs.org/downloads.html