When roasting your shrimp, different sizes will need different cooking times. Keep an eye on it and just when it's turned pink and begun to curl into a u0022Cu0022 shape, take it out. Overcooked shrimp will turn white or gray and tend to take on an u0022Ou0022 shape. It can be difficult to gauge the first time around, so I'd recommend buying a little extra to practice before you plan on serving them.