It was reportedly taken by a sixth year - the Scottish equivalent of year 13 - pupil who was sharing a room with his fellow student and returned numerous times to find the teacher in bed.
Classmates told The Telegraph that the teacher had bought drinks for students and rubbed the pupil's legs under the table at the prom.
"It was just a one night stand," a former pupil at Whitburn Academy, West Lothian, said.
The investigation initially involved police but did not lead to criminal charges. For legal reasons, the pupil cannot be named.
Graham, who was not present or represented at the hearing, denied the charges and claimed to have no recollection of events after 10.30pm, having drunk four glasses of wine.
She is understood to be living abroad with her husband Andrew Wilkie, who is training for the clergy.
They were married in July 2015 and she claimed in a statement that, as a Christian, she was saving herself for their wedding.
"In all the time I have known her, Mrs Graham has always put her Christian faith above all other things," Wilkie said in a statement to the panel.
"I have never had any doubt that the allegations made against Mrs Graham were false."
The General Teaching Council for Scotland (GTCS) investigated the teacher for travelling with the boy and other pupils from an upmarket Edinburgh hotel, where the prom took place, to a nearby Travelodge.
The former teacher is alleged to have spent three hours alone with the teenager - drinking with him, sharing a bed with him and "repeatedly engaging in sexual activity" with him.
Mr Thomson said evidence from students outlined how they saw "Pupil A and Mrs Graham lying on the bed, one on top of the covers and one underneath the covers".
Graham previously admitted that four glasses of wine would not normally intoxicate her to that level, and that her hair was similar to the one pictured, but denied recognising the teenager in the same photograph.
Carla Roth, the GTCS lawyer, said Mrs Graham's actions had a "public nature", and left some schoolchildren feeling "uncomfortable" and "somewhat shocked".
Detective Sgt Keith Mailer, who investigated the incident for Police Scotland, said there was no evidence the teacher's drink had been spiked when she was tested at hospital.
CCTV footage showed Graham kissing the pupil and the officer added that the way she moved and "conducted herself" suggested someone who was making conscious decisions.
The footage gave no indication that she was "under the excessive influence of drugs or alcohol", he added.
Graham said if the photograph was of her, then she was clearly unconscious.
She described herself as the "victim", adding: "The person in the bed in the photo is clearly not in control of the situation."
Graham, who resigned from her position after the allegations, was yesterday unavailable for comment.
A spokesman for West Lothian Council said: "Ms Graham is no longer employed by West Lothian Council and it would not be appropriate to comment further."
