One of the changes in the policies of the British after the suppression of the rebellion of 1857 was :
British Crown took over the control of administration − The British Parliament passed an Act in 1859, under which, the powers of the East India Company were transferred to the British Crown. The British government was now directly responsible for ruling India.
The British monarch, Queen Victoria, was declared the head of the British government in India and the Governor General became the Viceroy, the representative of the monarch in India.
Thus we can say that East India Company used to appoint "Governor Generals" to govern Indian territory under their control, however when India became a direct subject of British crown after 1857 the position of the governor general changed into Viceroy,whose relationship was not with the British government, but directly with the monarch.