The Sentence Diagram Generator visually represents the sentence "Whenever I feel sad, my mom gives me a hug." as follows:

          +---------------------+
          |        Whenever      |
          +---------------------+
                    |
                    |
                    v
          +---------------------+
          |         I           |
          +---------------------+
                    |
                    |
                    v
          +---------------------+
          |        feel         |
          +---------------------+
                    |
                    |
                    v
          +---------------------+
          |        sad          |
          +---------------------+
                    
          +---------------------+
          |        my           |
          +---------------------+
                    |
                    |
                    v
          +---------------------+
          |        mom          |
          +---------------------+
                    |
                    |
                    v
          +---------------------+
          |        gives        |
          +---------------------+
                    |
                    |
                    v
          +---------------------+
          |        me           |
          +---------------------+
                    |
                    |
                    v
          +---------------------+
          |        a            |
          +---------------------+
                    |
                    |
                    v
          +---------------------+
          |        hug          |
          +---------------------+

(Note: The above representation is a simplified text-based diagram. The actual Sentence Diagram Generator would provide a more visually structured diagram.)