One Public IP for multiple privates

How do you set up a Cisco routers to do NAT using one public IP address for multiple private networks.
I have networks 192.168.42.0/24, 10.100.0.0/16 and 172.16.0.0/16. The Cisco router is directly connected to 192.168.42.0/24 network and I can get all the clients in that network to get out fine. But none of the other networks does work.

My configuration is something like this:

ip nat pool puye1 199.45.204.79 199.45.204.79 netmask 255.255.255.224
ip nat inside source list 40 pool puye1 overload
ip classless
ip route 0.0.0.0 0.0.0.0 199.45.204.65
access-list 40 permit 192.168.42.0 0.0.0.255
access-list 40 permit 10.100.0.0 0.0.255.255
access-list 40 permit 172.16.0.0 0.0.255.255

Do any one know how to do this?

Thanks in advance.