Shouldn't hurt anything--you'd have to add a redicolous amount to get any flavours from it.
You'd add the colouring just before bottling, maybe before racking the final time so it gets gently mixed in.
There is one secret ingredient that makes anything better......time.
Primary: House Cider; Rhubarb Wine (two batches), Carrot Wine
Secondary: Malliard Botchet, Walnut Belgian Graff
Tertiary (or higher): Mahlab Metheglin
Drinking: House Cider, Oaked Ginger Cider