Timedelta formats in plotly plot

I am trying to visualise some data for work, and my manager wants me to create a continuous timeline from 2018 to 2021, indicating where there are gaps. I would like to plot a graph with my Date column on the x axis, and Time_difference on the y axis, with the Time_analysis column as the key/colour code. I tried some code, but unfortunately, the format of the Time_difference column doesn’t come out on the plot the way I’d like it to. Is there a way I can change it so that it reads ‘0 days 00:00:00’ on the y axis, for example?

Also, what is the best way to save plotly plots to a png?

Thanks!