I've searched through several dictionaries but the closest I've gotten is taupo, and I'm not sure if that's a real Esperanto word.
If you mean the color, you could use
talpa, since it comes from the animal. That's what Italian does, for example.
Depending on the needs of the context, you might want to use another adjective, such as
bruneca aŭ eĉ
bruna for the light taupe, or
grizeca for taupe grey. Taupe by itself does not longer refer to a single color.
If you need to stick to taupe, then you can go for