You can view the detailed instruction on how to create Contact List Tags to group them visually.
Setup: Create Tags
Please follow this guide for creating tags. Tags are a simple way to tag contact lists to visually group them together. It does not contain any rules but it is simpler if you have contact lists that can be tagged together.
To create a tag go to the List Management > Tags section. Click the “Create New Tag” button. Type the name of the tag you want. Then click on ‘Add’
2. Once a tag is created, you can click on ‘Edit’ if you want to modify it.
3. In order to use the tags you created in ‘Contact List’, go to List Management > Contacts Lists. Select any row of your contact list and click on ‘Edit’. A popup like the one below will appear. Under ‘Tags’ you can select the tags you want and hit on ‘Update’