If you want to modify syntax colors you can do so by changing fonts and color settings in Tools → options → Environment → Fonts and Colors. But it is a cumbersome, error prone and time consuming process. For small tweaks though it is still a valid options.

You can also use Color Tweaker Pro extension which makes customizations really easy, and comes with a lot of templates but maybe this is overkill for your case and also it is a paid product.