Some of the literary devices that Shakespeare uses in this passage would be:
Simile: "as swift in motion as a ball"
This is used in order to convey an image of very swift, quick movement. This conveys the idea of desperation, as Juliet cannot wait for the nurse to return.
Allusion: "And therefore hath the wind-swift Cupid wings."
In these line, Shakespeare makes an allusion to Cupid, a creature from Greek mythology, often associated with love. This highlights the feelings of love that Juliet is experiencing.
Metaphor: "Therefore do nimble-pinion'd doves draw love,"
In this line, Juliet compares the nurse (who is acting as a messenger), and all other messenger that carry a message of love with doves, as they are also known to carry messages.