In the "colors" folder you'll find .xml files which you can customize for your desired theme.
And then you can choose your theme from the Appearance menu.
Some related articles and Color Scheme sources:
- http://www.phpstorm-themes.com/content/help
- https://laracasts.com/forum/?p=1601-color-scheme-php-storm/0 (and see the Dayle Rees template references in that discussion)
- http://laravelsnippets.com/snippets/phpstorm-custom-live-templates-and-theme-mostly-laravel-related-v2