This is fairly wide open and I think that you can go with it in different directions.  If there is an assignment rubric or task description that states particular elements that need to be addressed, but if not, this is very open to interpretation.  Chapter 1 could be entitled "A Dream and a Song" to represent Old Major's vision and the song, "Beasts of England" that becomes a rallying cry.  I like the idea of Chapter 2's rebellion being critical and a title of "We're Not Going to Take It" helps to bring this out.  Chapter 3 could be entitled "Seven Commandments and Three Pigs" to illuminate that edicts that must be followed on the farm by all the animals and the leadership of the three pigs to help enforce this.  Chapter 4 could be representative of the notion that "We're Not Going Quietly" to show how the humans are planning to take back the farm.  In Chapter 5, the battles that emerge between both humans and animals could bring out the title of "Clash of the Titans," while in Chapter 6 the dominant idea of how the animals are struggling under the weight of crushing reality could be embodied with "Hard Times."  Chapter 7's title must address the issue of Napoleon's brutality, so something like, "Hard Times and Harder Leadership" would be appropriate.  Chapter 8 focuses on the clear hierarchy of the farm in which the pigs are on top and everyone else is underneath, so a title like "A Pig's Life" might work here with Chapter 9 centering on Boxer's death and a title of "I Cannot Work Harder" can serve to highlight this.  I love the idea in Chapter 10 of how the pigs and the humans mirror one another, unable to distinguish between them and so the final title I would suggest would be "Meet the New Boss- Same as the Old Boss."