I've just had a quick look at this and the only way i can think of changing the color is like this
data.setRowProperty(0, 'style', 'background-color:yellow;background-image:none');
or to change it when the node has been selected
data.setRowProperty(1, 'selectedStyle', 'background-color:yellow;background-image:none');
(the number 0 and 1 in each of the above example relate to the row number, 0 being the first row)
hope this helps