It is less well-known that at least one Gospel manuscript had attempted a colour-coding of its presentation. This is Paris, Bibliothèque Nationale de France, Codex Grec 54 (bilingual diglot; 13th Cent. = Gregory/Aland minuscule 16), dubbed by Gregory 'the rainbow manuscript' (Canon and Text, 372). It uses a range of different colour to indicate different speakers:
- bright red ink: simple narrative text
- darker red/crimson ink: the genealogy of Christ, the words of angels, the words of Jesus
- blue ink: OT passages, words of disciples, Zachariah, Mary, Elizabeth, Simeon, John the Baptist
- dark brown ink: words of Pharisees, people from crowd, Judas Iscariot, the devil, shepherds, scribes, the Centurion
For full discussion of the manuscript and its production see Kathleen Maxwell, 'Paris, Bibliothèque Nationale de France, Codex Grec 54: Modus Operandi of Scribes and Artists in a Palaiologan Gospel Book' in Dumbarton Oaks Papers, 54(2000) 117-138; esp. p. 123 for the four colours and speakers (pdf here). It is a particularly interesting manuscript because it was unfinished and therefore reveals more of the scribes workings than is usually seen.Unfortunately I have not been able to find colour pictures (black and white plates published with Maxwell's article are here).
Maxwell doesn't discuss the hermeneutical impact of such a colour-coding scheme on readers/viewers.