Laravel uses Whoops package for various error messages. For a long time, the package was used with a custom color-scheme by Dayle Rees.
Newer versions of Laravel (from 4.2) use the latest Whoops version and default color-scheme, the grey and blue one,
to avoid various errors with the next updates of Whoops.
For everyone, who liked the orange theme (the colors, fonts, font-sizes, etc.) - here it is.
Simply copy the css file to that vendor folder in your laravel directory, according to your whoops version:
vendor/filp/whoops/src/Whoops/Resources/css/