Well if you are already preparing for CAT, XAT or any other exam, then cracking SNAP in just one month should not be very challenging. All you have to do is focus on General Knowledge and keep yourself updated by reading the newspaper everyday. Try to give as many mocks as possible and analyze them thoroughly.
However, if you have not been preparing for any other MBA entrance exam, then preparing for all the sections in just one month can be a difficult task. You should either be a child prodigy or a person with extraordinary skills and intelligence if you are to score well in the exam.
So work on your strengths and give in your best. Even if you don’t clear the exam, you will atleast get an experience and can try again next time.
You can also follow this link to get quick access to all the SNAP related material for preparation.