Last, if you print log messages to the standard output using the
verbose option, you'll get some fancy colors:

var casper =require('casper').create({
verbose:true,
logLevel:'debug'})
casper.log('this is a debug message','debug');
casper.log('and an informative one','info');
casper.log('and a warning','warning');
casper.log('and an error','error');
casper.exit();

This will give the following output: