When looking for the literary elements in a story, it is necessary to break down the story into its parts or elements. These include the plot, the characters, the setting and the theme. Typically, the literary elements are the what (plot), whom (characters), who (narrator), where (setting), when (setting), how (tone) and for what reason or why (theme, purpose)?
In "Thank You M'am" by Langston Hughes, it is Mrs. Luella Bates Washington Jones who stands out as a character who takes every challenge and turns it into a positive learning experience. She and Roger, the boy who steals her purse, are the whom of the story, and it is around them that the plot develops. The story is a life lesson, intended to teach everybody about humility, kindness, and to show that there is no excuse for bad behavior, regardless of circumstances or desires, and certainly not in the case of Roger's "blue suede shoes." This is therefore the theme, revealed by the characterization and plot development and Mrs. Jones's compassion and understanding of Roger's circumstances.
There is a third person narrator and Hughes ensures that this narrator understands his subject well, using colloquial language. The story takes place at night, between the street in a working class neighborhood and Mrs. Jones's home (the setting). Mrs. Jones surprises Roger with her attitude and the tone is such that, at first, the reader is not sure what to expect - much like Roger does not know what punishment is about to be metered out to him. Mrs. Jones is clearly a woman of strong moral integrity and she expects a high standard from others. Roger's response also develops the plot of the story as he, reluctantly at first, accepts her kindness and recognizes the position of trust she impresses upon him. He appreciates this and responds positively to Mrs. Jones.
The reader realizes that Mrs. Jones is a self-effacing woman, of modest means but very generous with her money and time and the reader finishes the story hopeful that Roger has learnt his lesson and not only will he not steal but he may even extend that same courtesy to another person in need. Hence, the purpose of the story is clearly understood.