It really depends whether your talking about live or dried bamboo. Additionally, bamboo from different areas of the world look different in color, size, and growth patterns. In general:
Live bamboo is green and varies from a yellowish or lime green color between the growth rings to a dark green for the rings themselves.
Dried bamboo varies from a very light - almost yellowish - brown (light khaki, light tan, etc.) in the areas between the growth rings to a dark brown - nearly black - color at the rings themselves.
I would just do a Yahoo or Google search for bamboo and find some pictures of live and dried bamboo to check the colors.
Hope this helps...