It means she acting like the most important person in the world. Think of most famous female emperor of China.

The Queen of Sheba is a figure in the Old Testament, a part of the Holy Bible sacred to both Christians and Jews. She was a queen of Egypt who visited wise King Solomon. It is sometimes thought that the Shulamite Princess in the Song of Solomon--an erotic poem that is part of the Bible--was the Queen of Sheba. At any rate, the Queen of Sheba was an important and powerful monarch. In the U.S., in everyday speech, "the Queen of Sheba" is sometimes used to mean "a queen, and not just any ordinary queen, but an especially powerful, high-ranking queen." It would be used in expressions like "She thinks she's the Queen of Sheba," or "You get right down there now and take out the trash, and stop acting as if you're the Queen of Sheba."

Yes I would say so, acting like royalty and NOT using "please"or "could you... would you please... etc" when asking people to do things.