The woman was going to visit a friend on Sunday 5 June when a man approached her on St James Street between around 10.30am and 10.50pm.
He followed her down the side of Brodsworth House onto a grassed area where she was sexually assaulted.
The attacker is described as white, of average build, with a pointy nose and blonde hair. He was wearing a dark hooded jacket and dark tracksuit bottoms.
Do you recognise the man in the e-fit? Were you in the area at the time? Did you hear or see anything suspicious?
Call police via 101, quoting incident 1351 of June 5 2016. You can also contact Crime Stoppers anonymously on 0800 555 111.