The Venn Diagram 4 Union Circle is a set of four overlapping circles. The circles are colored blue, green, red and orange. The blue circle is in the center and has the shape of a rectangle. The green circle is on the top left side of the blue circle and has a rectangular shape as well. The red circle is on the top right side of the blue circle and has an oval shape. The orange circle is on the bottom left side of the blue circle and also has an oval shape.