Graham began his coaching career with the Otahuhu Leopards 18s in 1973. In 1977 Graham became Otahuhu’s head coach. Grham led Otahuhu to the 1977 and 1978 Premierships. Graham coached Otahuhu over 3 seasons. In 1979, Graham joined the Norths Devils. Graham led Norths to the 1980 Premiership. Graham coached Norths for 4 seasons. In 1986, Graham was appointed coach of the Wigan Warriors. Graham led Wigan to the; 1987 Championship, 1988 and 1989 Challenge Cups. Graham coached Wigan for 128 games over 3 seasons (104 wins, 3 draws). In 1990, Graham was appointed coach of the Manly Sea Eagles. Graham coached Manly for 70 games over 3 seasons (40 wins, 3 draws). Graham coached the North Queensland Cowboys for the 1996 season for 21 games (6 wins). In 2008, Graham coached the Bay of Plenty Stags in the Bartercard Premiership for 5 games (1 win).
In 1983 Graham was appointed coach of New Zealand. Graham coached New Zealand in 16 test matches (7 wins, 1 draw). In 1991, Graham was appointed coach of the Queensland Maroons. Graham coached Queensland to victory in the 1991 series. Graham coached Queensland over 2 series (3 wins). Graham coached Western Samoa during the 1995 World Cup in 2 games (1 win).
In the late 1990s, Graham was a part owner of the Auckland Warriors. In November 2009, Graham was appointed Chief Executive Officer of the Manly Sea Eagles. Graham stood down in April 2011 due to health issues. In January 2017, Graham was appointed co-owner of the Bradford Bulls. Due to health issues, Graham returned to New Zealand shortly after the partnership was formed; he stood down in August 2017. In 2019, Graham was awarded a knighthood for his services to youth and education. In 2022, Graham was inducted as a New Zealand Legend of League.