Installing QLColorCode using Homebrew by running
brew cask install qlcolorcode and invoking Quick Look on the same file immediately thereafter shows this color coded output:
Follow the installation instructions on the project homepage to make sure your have correctly installed the plugin:
This is a Quick Look plugin that renders source code with syntax highlighting, using the Highlight library.
To install Highlight, download the library manualy, or use homebrew
brew install highlight
To install the plugin, just drag it to
~/Library/QuickLook. You may need to create that folder if it doesn't already exist.
Alternative, if you use Homebrew-Cask, install with
brew cask install qlcolorcode.