The odd looking yellow Diablo is in fact a custom tuned car built by Roland Affolter in the Swiss area.
He's the official importer for Automobili Lamborghini SpA in that region and also a top tuner for these exotic cars.
Take a look at my Lamborghini site for more information on this and other projects he did over the years.
http://www.lambocars.com
Go to the Diablo line-up pages and select the various Affolter Diablo's listed there.
Some people just like to be different from the rest, take a look at this one :