"But the Lord said to Samuel, “Do not consider his appearance or his height, for I have rejected him. The Lord does not look at the things man looks at. Man looks at the outward appearance, but the Lord looks at his heart."" Samuel Also seen in John
This is a political design. The use or lack of colour helps extenuate the point the creator wants to create. The use of flowers, as a severe contrast to violence and war, also shows the message of peace, not war. Powerful visuals in a simple way.