@Joshua Hultman -
Yes, please take a look at this link from Atlassian -
CLOUD Env - https://support.atlassian.com/jira-software-cloud/docs/add-color-to-issues-on-your-advanced-roadmaps-timeline/
Server/DC Env - https://confluence.atlassian.com/jirasoftwareserver/add-colors-to-issues-on-your-advanced-roadmaps-timeline-1044784269.html
Hope this helps.
Best, Joseph Chung Yin
Jira/JSM Functional Lead, Global Infrastructure Applications Team
Viasat Inc.