Storyboards in colour are usually elaborated to show the clients that it is going to be a lush film they invest in. Depending on the amount of detail of the colouration the price per frame may rise 30% to 70% as it takes quite some time to fill in colour.
Since my storyboards have a certain amount of colour even in black and white mode ( ink and a coloured layer in Photoshop are standard ), this is sufficient for most. Agencies often present their storyboards ( “agency boards“ – no director is involved here ) in color.
When working for film productions, this is rarely requested.