Pink is a great attracter for Grayling and I have regularly found pink flies to out-fish more sombre patterns - Sometimes in coloured water, but also in crystal clear but very cold water.
Here's a version of the tungsten back shrimps, bringing a splash of colour to pattern:
These shrimp imitations fish 'upside down':
Hook: Partridge YK4G #16
Thread: Moser Powersilk 10/0, olive
Underbody: Hare's mask, light
Legs: Grey squirrel
Ballast: Tungsten shrimp back, pink