For this magnificent painting, I would suggest using a blue and white color scheme as the mainstay. I would use a slightly darker shade of blue for the robes and a brighter shade of blue for the background. Then, I would use a light gray color for accents, like the faces of the figures, their hair, the staff, sword and crown. To bring some more vibrance and color to the piece, I'd use a bright red for the flower, a light pink for the baby, and an olive green for the accents around the throne and the staff. Finally, I would also use some pure white and black to create added contrast and give the colors a richer dimension.