Hello. The sentence shown above is already written in figurative language, since figurative language is one that is inserted in a sentence that does not have a literal sense, but figurative and subjunctive. The phrase you showed above doesn't have a literal meaning, as the sky doesn't miss the sun in the real world. Thus, the phrase is already in figurative language and presents a figure of speech called personification, which allows the sky, an inanimate being, to present feelings. If you want to translate this phrase into literal language, you can write "the sky gets very dark at night."