Australia is an interesting country when it comes to voting, some would assume that Australia would vote like western European countries and their usual picks, but it actually seems not really the time.
Also, what impact would you say diaspora in Australia has on the voting? So far that didn't seem to obvious either (I refer to mostly Greeks, Italians and Balkans who seem to be quite big European diaspora groups in Australia).
The only truly noticeable diaspora effect would be that of the UK. Comparing the Australian televote to the overall televote shows 9th instead of 25th for Electro Velvet in 2015, 7th instead of 25th in 2016, 8th instead of 20th in 2017 and 5th instead of 20th in 2018.
The other diasporas don't seem to have a result that particularly sways the voting in a way that causes the Australian televote Top Ten to be out of step with the overall televote. Probably that's partly because the multiple diasporas mean that to the degree a diaspora favours the they emigrated from or their family emigrated from, a good deal of that is cancelled out by voting from other diasporas. It may also be due to younger generations identifying as Australian as much as or more than any other national/ethnic identity.
Australia's Eurovision fanbase is one that in terms of demographics favours those who identify as LGBT+ and/or are young. Comparing the Australian televote to the overall televote shows song that are perceived as particularly LGBT+ can get a considerable boost (Together was 3rd place instead of 16; Monsters was 7th instead of 21st, Roi was 8th instead of 18th).
The Australian televote and Jury generally follows the overall jury top ten, rather than favouring particular nations with the exception of the televote for the UK. The deviations indicate that the televote favours fun, uptempo songs over ballads and songs that have crazier staging but still have strong vocals. The Jury is more prone to being subject to individual tastes.