"The color of Esperanto is green."
Translation:La Esperanta koloro estas la verda koloro.
The English sentence is in the genitive ("of") but the Esperanto sentence is not. What's up with that?
Genitives (in the sense of possessive ideas) can also be formed with adjectives - see how you used "English sentence" and "Esperanto sentence" instead of "sentence in (of) English/Esperanto". It's the same process.