You can change every aspect of the chart that your heart desires. We have made several templates that use varying colors, be it for different lighting situations or just purely for aesthetics. So, the first place to start is to just try a different chart template.
If that doesn't get you to where you want to be, you can start tweaking the indicator colors. NinjaTrader7 has allowed us to program our indicators with versatility in mind. Just by visiting the indicator settings, you should see several options for every indicator we've designed.
Lastly, right click the chart and click Properties, (or hold Ctrl and press T). This will bring up the Chart Properties configuration window. Here you can change the background, axis, data labels, cross hair colors, and many more. You can also adjust the font size and label formats. Just play around with it until you've found something you really enjoy.
Tip: After you found preferable settings, save your configuration to a chart template, so you can always quickly go back to it.
With so many options available, you should be able to get the charts exactly the way you want.