Hi @russelllv45,
You can do so by using the custom CSS classes assigned to each announcement and writing out custom CSS to change the background color for each announcement.
Outside of using the custom classes defined on each announcement and writing the custom CSS to tweak the backgrounds, you can use Timeline Express Pro to tweak the styles for each announcement on the timeline.
You can also tweak each announcement further by customizing the announcement, tweaking additional styles, altering the animations and a few other things.
Feel free to take a look at the pro version and some of the features and our demos we have setup:
https://www.wp-timelineexpress.com/
Thank You for Your Response