。
She got married soon after graduating from college.
Literal
She [topic-は] college-graduation-after soon married.
大学卒業後 is a Sino-Japanese compound: 大学 ('college') + 卒業 ('graduation') + 後 ('after'). The ~後 suffix attaches to nouns (or noun-form verbs) for 'after X' — formal, written-flavored. The colloquial alternative is the te-form: 大学を卒業してから. まもなく ('soon, shortly') is a single-word adverb with a slight literary feel; in spoken Japanese, すぐに or もうすぐ would be more natural.