SOURCE

let diameter=[];
let c=[];
function setup(){
    createCanvas(500,500);
    rectMode(CENTER);
    background(120);
    noStroke();
    for(let i=0;i<72;i++){
        diameter[i]=random(255);
    }
    for(let i=0;i<24;i++){
        c[i]=random(60,100);
    }
for(let i=0;i<24;i++){
        let index=i*3;
        fill(diameter[index],diameter[index+1],diameter[index+2]);
        ellipse(random(width),random(height),c[i],c[i]);
    }
}
function draw(){
    }

<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/1.1.9/p5.min.js"></script>