The Sentence Diagram Generator visually represents the grammatical structure of the sentence "The not red shirt looks ugly." It breaks down the components as follows:

1. Subject: "The not red shirt"

   • Determiner: "The"
   • Modifier: "not red"
     • Adverb: "not"
     • Adjective: "red"
   • Noun: "shirt"

2. Predicate: "looks ugly"

   • Verb: "looks"
   • Complement: "ugly" (Adjective)

This structure can be visually represented in a diagram format, illustrating the relationships between the subject and predicate, as well as the modifiers within the subject.