You might want to analyse some of the description of the surrounding landscape that the novel contains. For example, figurative language is used in the following piece of description:
Slow water in the fat country. The slough by the roadside motionless and grey. The coastal plain rivers in leaden serpentine across the wasted farmland.
Note the way that figurative language is used to compare the coastal plain rivers to leaden snakes which is used to help us visualise the way the rivers meander across the landscape. The way that they are compared to snakes also of course brings in an element of sinister threat or of danger to the setting.
For one more example, consider the description given when they enter an abandoned house and start a fire in its fireplace.
The flames lit the darkening glass of the window where the boy stood in hooded silhouette like a troll come in from the night.
The boy is compared through use of a simile to a troll, which is in keeping with the mood of suspense and terror of the novel, but also helps us understand that such a sight and such a feeling of warmth are so alien to the boy, having walked around for so long with his father, that he does not seem to fit in to such a "normal" domestic setting. Before lighting the fire, the boy and the father brought in many "dead limbs" to light the fire, reinforcing the novel's focus on death.
There are two examples for you. Hopefully you will be able to go and find some others now. Good luck!