Colors Within "The Great Gatsby"

“We both looked at the grass- there was a sharp line where my ragged lawn ended and the darker, well-kept expanse of his began. I suspected he meant [cutting] my grass." (page 82)

F. Scott Fitzgerald refers to colors in both a direct and an indirect way throughout his novel, "The Great Gatsby". But what is his intent? What do those recurring colors represent?

The excerpt above was taken from a scene describing Gatsby's behavior before Daisy's arrival to Nick's house for tea. Gatsby, a West Egg millionaire, slightly criticizes Nick's ragged lawn and straightforwardly tells Nick that he wants to cut it, trim it, make it more pleasant to look at. Nick immediately notices how his grass, compared to Gatsby´s, looks poor. I understand a "ragged lawn" as some sort of disorganized,  dirty, brown patch of weed. Its owner certainly does not have the money or the time to take care of it and make it delightful to look at. However, when Nick describes Gatsby's "darker, well-kept expanse" I imagine something totally different; rich green extensions of fertile lawns, those that people would rather look at than step on. Moreover, by how the scenery is described throughout the novel, I imagine Gatsby's lawn to be somehow above Nicks, as if it were a little mountain, as if Gatsby himself were "above" the narrator. What I believe Fitzgerald is attempting to deliver is just that; social classes. A perfectly kept, dark, rich green lawn with the white house gingerly built over it is the classic image of the American Dream; of those who made it. Meanwhile, a ragged lawn portrays the ghettos and suburban areas where people hardly have enough money to eat let alone embellish a lawn. Gatsby does not even ask Nick if he could trim his grass, he just says it. This shows how his dark, beautiful lawn is somehow better than Nick's and Gatsby is "considerate" enough to make it prettier, or richer, all because of what Daisy might think. Fitzgerald is delivering, through imagery and what colors may tell us, how Nick´s and Gatsby´s incomes differed and how one of them apparently accomplished the American Dream.