Quadrille.outline = 'cyan';
let quadrille;
let colorPicker;

function setup() {
  createCanvas(400, 400);
  quadrille = createQuadrille(4, 4);
  colorPicker = createColorPicker(Quadrille.outline);
  colorPicker.position(width - 60, 10);
  colorPicker.input(() => Quadrille.outline = colorPicker.value());
}

function draw() {
  background('red');
  drawQuadrille(quadrille);
}