We used to create "special formats" with the first version, but I forgot to add this feature in our newly coded version. And now it has been added.
If you don't want to recreate your config.yml file, you should add "special-formats" to "Chat" section, for example:
Code (Text):
Chat:
enabled: true
format: '%rankprefix% %vault_rankprefix% &r%playername%&7: &r%message%'
special-formats:
Owner: '%vault_rankprefix% %playername%&c: &4%message%'