We're getting two new Werewolf Form skill styles in Update 51! The first is Werewolf Form, Red:

This is sourced from the Wolfhunter Solo Dungeons, via the Skill Stylist IV: Werewolf Form achievement. Collect 10 fragments from solo March of Sacrifices and solo Moon Hunter Keep respectively to unlock that fur color.

Further, we got to preview a brand new Werewolf Form Skill Style, acquired from Purchase, Promotion, or Event, called Werewolf Form, Ragefire:

I will
absolutely be grabbing both of these styles as soon as they become available. Thank you ZOS!!
So, in total, we'll have 5 different Werewolf Form Skill Styles, 4 of which are free to unlock without any DLC, as the Wolfhunter DLC will be made base game by the time the Solo Dungeons feature releases. We have all these styles to pick from:

If you're indecisive on which style you want to use,
I made an addon which allows you to automatically swap between your owned Werewolf Form Skill Styles, which I would highly recommend if you like collecting these Werewolf Form Skill Styles!
PC/NA — Lone Werewolf
Werewolf Should be Allowed to Sneak Prowling added in Update 50!
Please give us Werewolf
Skill Styles (for customizing our fur color) Added in Update 50!,
Grimoires/Scribing skills (to fill in the holes in our builds), and
Companions (to transform with).