Editorial Note: This article is written with editorial review and topic relevance in mind.
A people person is someone who is outgoing and has good communication skills. Peoples is used when we talk about two or more. People is a collective noun.
People's Friend Special Magazine Issue 269 Mags Direct
When we talk about a specific group of people, we consider it as singular and therefore, no need to add s. What is the plural of people person? He was always energetic and positive and he was a people person.