Silvered Leaf Monkey
Silvery lutung (Trachypithecus cristatus (selangorensis or cristatus)

Silvery langurs are arboreal, diurnal, herbivores living in coastal forests and mangroves and riverine forests of Southeast Asia. They are classified as Near Threatened due to habitat destruction.
 

Another photograph of a Silvered Langur is available at Fine Art America:

Photography Prints