I don't have a template at hand but I know what needs to be on the invitation letter. Letter should be addressed to embassy and should contain roughly -
Company from EU is inviting Mr.X with Passport number - 1234 DOB - ddmmyyyy for n number of days for abc purpose. The details of the visit are highlighted in the itinerary below (add a table with dates, planned activities, people you are meeting, location.
All the expenses will be born by EU company. Kindly approve multiple entry business visa for x days.
BR,
Name of Ceo
Sign
Stamp of company
Contact number