Why did GOD choose to creat black,white,yellow and coloured people? Why not human beings are GENOUS?

If God is all that supreme, powerful and a ntelligent designer why did he creat human with such diverse features and colours or is it that 7 days was too short a period to look in to detailed production. OR GOD left the human making process to some body and only kept the theology and public relation department with him ??