Colman competed at the 2004 Athens Paralympics, where he won a gold medal in the men's 800 m – T53 event, for which he received a Medal of the Order of Australia, a silver medal in the men's 4 x 100 m relay – T53–54 event, went out in the first round of the men's 100 m – T53 event, finished seventh in the men's 200 m – T53 event, finished sixth in the men's 400 m – T53 event, went out in the first round of the men's 4 x 400 m relay – T53-54 event.