"Mrs. Robinson" may be the song most associated with the Mike Nichols film The Graduate, but it wasn't the song used in the iconic final scene. That song was the first Simon and Garfunkel #1 hit, "The Sound Of Silence", which Nichols convinced the duo to rerecord for the soundtrack. Paul Simon wrote the song in the echo of his dark bathroom - hance the sound of silence.
The song is sad and stark in its imagery, while retaining a harmonic beauty. It picks up tempo as it roles along, ending with an abrupt deadening in tempo.
In context, here is that last scene of the movie. The song is slightly different in this version, and it matches the feeling of the scene - the unknown, not knowing what's next, the good and bad of the reality of what just happened hitting you. There's some excitement to this, and at the same time, fear.