The label "New Holland" dates it probably prior to 1824, which is when the UK officially changed the name of the continent to Australia.

It looks to me like the same map as linked by Crayons, published 1795. From the images of those two maps, it looks like the other continents may have been colored at one time, too, but the colors have faded. My guess is that it was hung somewhere that it was exposed to the sun, which bleached out the colors.