I'd recomend giving a read to the Animorphs Series, specifically the Megamorphs line and a few of the Chronicles series. Either way, the main-line series features six main characters who swap first person narrative duties during the main line books (originally in a rotation of five books, the four human characters get one book a piece, while the non-humans, a human permanently turned into a hawk and an alien, would take the final book every other rotation. Or to better explain, each of the four humans would books numbers with the same two digits (1s and 6s, 2s and 7s, 4s and 9s, and 5s and 0s) and the non-humans would get one book (Hawk got 3s and Alien got 8s). This changed towards the end of the series so that each character would get 1 book in a rotation of six (In the first rotation to use the change over, the Hawk got the 3 book in rotation and the alien got the 6th book in rotation).
The Megamorphs line were a series of five books in which all six main characters took turns narrating the story, a chapter at a time, with each chapter naming the narrator as well as showing their picture from that book's cover art. There were occasional mainline books that did this two and the default narrator would let the audience know this was happening well in advanced (Book 19 was the first to do this). The Chronicles line were a series of prequels told almost always by non-main charaters (though one begins with a main character meeting some side characters who tell him a story from thier culture so he narrates the first and last chapter) and could either be a lone narrator or a mix of shared narrators. In the later case, the same chapter marking format would take place.
As a general rule, all narrators should be consistent within chapters, and if you plan to do this frequently, you should denote who is your storyteller. If the characters all only narrate one story contained to one chapter, you might consider titling each chapter in a way that signifies it's this persons tale (I.e. The Farmer's tale, the Teacher's tale) or in a way that alludes to the profession and possible story (I.E. The Great Harvest, The Lesson Plan, Rank and File, Chains of Command).
These aren't hard rules as the Harry Potter series was 90% told from Harry's POV but there were a handful of chapters that weren't (Chapter 1 Book One was told from Uncle Vernon's with a switch to Third Person Objective, Chapter 1, Book 4 was told from a muggle's point of view, and Chapters 1 and 2 were told from an unnamed UK Prime Minister (who is remarkably similar to Jim Hacker from "Yes, Minister") and Malfoy's mother's Perspective respectively. None of these are overtly annouced in the chapter title, but they serve more as prolog to the main narrative.