The poem's imagery illustrates the dull monotony and discomfort of the father's life. As he heads home from work, for example, he's "Standing among silent commuters in the yellow light." Readers can envision the train bathed in sickly artificial light and filled with people who don't talk to or perhaps even look at one another. "Suburbs slide past" the train's windows as it moves further from the city. The image is dreary; this commute doesn't seem pleasant.
The poem's descriptions of the father himself are no less dismal. "His shirt and pants are soggy" from the "monsoon" season's humidity and rain, his jacket is "stained with mud," and his tote bag, brimming with books, is "falling apart." The weather is hot and sticky, and he looks shabby and uncomfortable. His eyes are "dimmed by age," lacking their former brightness or any spark of excitement. Instead of lighting up at the prospect of going home, they simply "fade homeward through the humid monsoon night." The word "fade" suggests that he's not exactly excited to get home because of all the good things that await him; rather, he's simply worn down and ready to get off this train.
Thick sibilance ("Standing," "silent," "Suburbs slide past his unseeing eyes," etc.) and /f/ alliteration ("falling," "fade") enhance this imagery. The poem is quiet and muffled rather than brash and attention-grabbing. Those soft, ghostly sounds slip past, subtly mirroring the way that the father's presence doesn't seem to affect anyone else.
His discomfort doesn't abate when he makes it home. His leather sandals are "sticky with mud," and readers can perhaps hear them squelching as he "hurries onward." His tea is "weak" and his "chapati" is "stale"; home feels as bland and tiresome as the train. Later, the speaker envisions him standing "at the sink," his body "trembling" as "cold water" pours over his "brown hands." It isn't clear whether he is shaking from exhaustion or emotion; regardless, this imagery makes it easy to picture the scene at hand and to sense the father's vulnerability. The speaker also points out that a "few droplets cling to the greying hairs on his wrists." That the speaker is zooming in on these details suggests his own love and empathy for his father; he notices that he is getting older.