Cayless captained New Zealand to victory in the 2008 Rugby League World Cup. Cayless became one of the New Zealand Kiwis' most-capped players, having appeared on 38 occasions by April 2009 when he retired from international rugby league, stating that he wanted to focus the rest of his football career on the Eels. With the Eels, he holds the record for the most games as captain of any team in the NRL. Cayless was never a prolific try-scorer; the most he ever scored in a season was 5. He also endured a scoring drought spanning over 80 games in his last several NRL seasons. In the final game of his career, Cayless finally brought the drought to an end, touching down in front of his home crowd. He also kicked a Field Goal in 2008 against the Newcastle Knights to send the match into extra time. Luke Burt then kicked the winning Field Goal.