uses ImageChart, not ColumnChart. It can be confusing, but image charts are wrappers around the Image Chart API (
) which are a completely different beast than the Javascript Visualization API. For the JS API, as Drew wrote, colors are assigned by series. You can use a stacked ColumnChart where the number of columns (series) is the same as the number of bars, and in each series put the value in a different location. Something like:
var data = new google.visualization.DataTable();
data.addColumn('string', 'Name');
data.addColumn('number', '');
data.addColumn('number', '');
data.addColumn('number', '');
data.addRow(['Danny', 3.7, 0, 0]);
data.addRow(['Betty', 0, 4.1, 0]);
data.addRow(['Miles', 0, 0, 4.8]);