Ah, I remember seeing this beauty rolling around a few years back! They've had a new design every year since 2020, and the past couple years have been a public competition! Here's the other years:

2021:

2023:

2024:

Edit: The building in the background of the OP and these first two is New Preston Tram Workshop. It's been there since the 1920s, but it's still the newer one! lol

Edit 2: I realised that the years might seem out of order. The 2021 above was unveiled in late 2020 for the 2021 Midsumma Festival. Hence "new design every year since 2020". The competition for the 2025 livery should actually be starting in the next few weeks. Submissions run from June through to August, then public voting on finalists in September, and finally the unveil in December sometime.