Australian common garden katydid, Caedicia simplex, Tettigoniidae
Although normally green, erythrism (a condition causing excessive production of red pigments) is not incredibly uncommon in this species or in grasshoppers and katydids in general.
Photos 1-2 by coffey09, 3 by lisa_bennett, 4 by william-harland, 5 by helenmacky, 6 by ssw-burlg, 7-8 by flossiepip, and 9 (normal coloration) by dougalt