The Sentence Diagram Generator visually represents the sentence "I set a record for winning five races in a row" as follows:

          +-------------------+
          |        I          |
          +-------------------+
                    |
          +-------------------+
          |        set        |
          +-------------------+
                    |
          +-------------------+
          |      a record     |
          +-------------------+
                    |
          +-------------------+
          |       for         |
          +-------------------+
                    |
          +-------------------+
          |     winning       |
          +-------------------+
                    |
          +-------------------+
          |       five        |
          +-------------------+
                    |
          +-------------------+
          |      races        |
          +-------------------+
                    |
          +-------------------+
          |       in          |
          +-------------------+
                    |
          +-------------------+
          |        a          |
          +-------------------+
                    |
          +-------------------+
          |       row         |
          +-------------------+

This diagram illustrates the grammatical structure of the sentence, showing the subject, verb, and the object along with its modifiers.