She is wearing Undercover yellow ruffles and Chanel earrings, photography and styling direction by Willy Vanderperre and Panos Yiapanis respectively. (source)
Click here to view last year covers featuring Kendall Jenner, Cara Delevingne, and Kim Kardashian. Click here to view 2014 cover featuring Miley Cyrus. Click the links to view last year covers featuring Cara Delevingne and Kate Moss.
Click the links to view 2010 covers featuring Naomi Campbell, Lara Stone (she got two versions), Natalia Vodianova, Amber Valetta, Daria Werbowy, Kristen McMenamy, Lara Stone and Jeneil Williams.