That would not be a wise decision kapil.this query has been posted so many time and there are so many threads on this.
Leaving a job would not go well with the ppl in the college. U have to give really strong reasons for that. and if u would say that u left it for preps then it there is a 99% chance they wud say gudbye.
another reason is CAt is not like board exams where u sit and study for 10 hrs a day and then in the end u make it. anything can happen on that day and if God forbid something goes bad and u end with a lower percentile, then u would be really frustrated...reaally really frustrated
I would suggest not to take ur job seriously.

while preparing for CAt, ur job shud be ur hobby and CAT shud be the place where u put in ur entire concentration. If u start giving ur 100% to ur job and expect to come back and study for CAt

, i dont think thts gonna happen