I would want to argue that the biggest symbol that we see in this chapter of this excellent novel is the face paint that Jack puts on his face and how that impacts his character. It is clear that the face paint is symbolic of a descent into savagery that becomes ever more evident and obvious as the novel continues. Note how this section of this chapter is described when Jack looks at his reflection in a coconut shell filled with water:
He looked in astonishment, no longer at himself but at an awesome stranger. He spilt the water and leapt to his feet, laughing excitedly. Beside the pool his sinewy body held up a mask that drew their eyes and appalled them. He began to dance and his laughter became a bloodthirsty snarling. He capered toward Bill, and the mask was a thing on its own, behind which Jack hid, liberated from shame and self-consciousness.
It is highly symbolic that the face paint is described as a mask which has "liberating" effects on Jack. With this mask on he is transformed into an "awesome stranger" who is able to dance with "bloodthirsty snarling." We clearly see the bloody violence and evil into which Jack and his band of hunters descend foreshadowed here, and we can see that the face paint is obviously symbolic of their descent into savagery.