I am not familiar with your neck of the woods, but most excavators or landscapers perform grading jobs.
I suggest you go to the Maine statewide list of contractors that are DEP certified at https://www.maine.gov/dep/land/training/ccec.html
Even if you're not within the shoreland zoning area this list is still a useful choice of finding and contacting contractors. You can search for contractors in your town or surrounding towns and ask if they grade roads or have a referral to a contractor who does in your area.