If you search this site you would get lots of format for this. and FYI i am enclosing one of the sample which i took it from this website. Hope it would be useful to you.
Show Cause Notice
Sub. – Performance issue
It has been observed that you have not delivered your best efforts as mutually agreed on the specified targets given to you to develop the business so far, resulting in insubordination and poor performance and gross negligence of duties, in your capacity as Regional Manager.
Poor performance of work is a complete loss of company’s business which you are making yourself liable for necessary action.
Failure to adhere to the conditions of this warning, development of new or related problems, and/or continued unsatisfactory performance will lead to more serious corrective action up to and including discharge.
You are further advised to improve your efficiency of work and submit a written explanation in 7 days on your Poor performance as soon as you receive this letter.
Kindly treat this as very urgent.
cc: Personal File
4th July 2011 From India, Tiruchchirappalli