Messages
Every message in the plugin (item names, command responses, etc.) are all configurable.
You can find the config at plugins/SkyFactionsReborn/messages.yml
.
Every entry has a description of what it corresponds to, making configuring all messages easy.
Text Colours / RGB
You can use HEX codes, as well as the standard Bukkit Color Codes in the messages config, with the following syntax:
Solid Colours
Example: {#FF0000}
Gradients
Example: {#6F00FF} Hello There! {/#0044FF}
NOTE
After modifying configs, consider validating your .yml configs through an online YAML validator such as YAMLlint.