The blue jersey has been synonymous with the Indian cricket team in the shorter formats of the game. The 1992 edition was the first World Cup to be held in coloured clothing and since then the Indian team jersey has always been a shade of blue. Hence the nickname - Men in Blue.

from Times of India https://timesofindia.indiatimes.com/sports/cricket/icc-world-cup/world-cup-why-virat-kohli-and-his-team-might-wear-orange-jerseys-against-england/articleshow/69645386.cms