Here is the location of many of the speed cameras in NSW on a map:
The Transport for NSW Centre for Road Safety also has a database of fixed camera locations (standard and those in school zones), mobile camera operating areas and red light camera locations here.
Roadwatch has a tool where you can enter your address and it will show you the cameras nearby.
Many speed cameras are marked using signs like this one:
You can also see some cameras by the side of the road like this:
Mobile speed cameras have a warning sign 250m before, then 50m before and 50m afterwards.
You can read the NSW speed camera strategy here.