You can use setTickLabelPaint()
and setLabelPaint()
like this:
Axis domain = plot.getDomainAxis();
domain.setTickLabelPaint(Color.blue);
domain.setLabelPaint(Color.blue);
Axis range = plot.getRangeAxis();
range.setTickLabelPaint(Color.red);
range.setLabelPaint(Color.red);