If you want to show a relation between entities in your drawing you can use 'Object Color Transition'. At the start of the command you have to select two colors. After selecting those colors you can select entities. By selecting those entities you not only make a selection you also define an order. When you confirm that selection those entities will change color. The first entity you picked will be colored with the first color you've picked. The second entity will have a color close to the first color. Every next entity will have a color that is closer to the second color you picked. The last entity will be colored with the second color you picked. This way there is a transition in colors from the first to the last entity.