Update: since the 308GT4 finished in 1980 and the Mondial got released in 1980 my guess is it's a picture from 1980. The motorshow location is still unknown to me.
The picture is published in the Ferrari book 1947 - 1997
Update 17-1-2018 : I received a nice update by one of the readers. So hereby confirmed it's Salon de Turin , 23 avril 1980.