Dot day

My idea for dot day is overlapping circles. I will use primary colours and in the overlapping part have a secondary colour. Example: red and blue circles with purple in the overlapping. I want to use large and small circles,some maybe even deformed. I plan to use bright colours such as red blue and yellow mostly. I also want to shade to make the edges more prominent. I have done a rough draft however the purple came out to grayish. I am going to keep mixing till I get the right shade.