Postcode Mapping | Victoria, Australia

Hi, I am looking for some software which will enable me to outline postcodes and groups of postcodes to delineate franchise territories. Can anyone please offer some advice?

Something like coast ?
You can play with -E option to have country and territories
e.g :

gmt coast -JM10c -EAU -W -B -png border_AU

For Victoria only : -EAU.VIC