The Face service is part of Cognitive Services and can be found on the Azure portal:
After logging on, use the search field at the top to find Cognitive Services, and follow that link:
Next, click on the Add button (screenshot below) to see the different services that are available in this section.
You'll get to a new page with a search field where you can search for Face. Clicking on that link takes you to the Face recognition info page, where you can sign up to the service by clicking on the Create button:
After signing up for the service, you can obtain a key for the Computer Vision API from the portal, which needs to be copied and pasted into the Color Factory configuration.