The Sentence Diagram Generator visually represents the sentence "I am learning to construct proper sentences." as follows:

        +---------------------+
        |         I           |
        +---------------------+
                |
                |
        +---------------------+
        |         am          |
        +---------------------+
                |
                |
        +---------------------+
        |      learning       |
        +---------------------+
                |
                |
        +---------------------+
        |        to           |
        +---------------------+
                |
                |
        +---------------------+
        |      construct      |
        +---------------------+
                |
                |
        +---------------------+
        |       proper        |
        +---------------------+
                |
                |
        +---------------------+
        |      sentences      |
        +---------------------+

This diagram illustrates the hierarchical structure of the sentence, showing the subject, verb, and the infinitive phrase that acts as the object of the verb.