Hola, comparto mi resultado.
<canvas width="600" height="400"> </canvas>
<script>
var pantalla = document.querySelector("canvas");
var pincel = pantalla.getContext("2d");
pincel.fillStyle = "lightgrey";
pincel.fillRect(0, 0, 600, 400);
//Cabeza
pincel.fillStyle = "green";
pincel.fillRect(125,150, 350, 300);
//ojos
pincel.fillStyle = "black";
pincel.fillRect(175, 160, 90, 90);
pincel.fillStyle = "black";
pincel.fillRect(335, 160, 90, 90);
//nariz
pincel.fillStyle = "black";
pincel.fillRect(265, 250, 70, 100);
// boca
pincel.fillStyle = "black";
pincel.fillRect(225,290, 40, 110);
pincel.fillStyle = "black";
pincel.fillRect(335, 290, 40, 110);
</script>
</body>
Saludos,