Yellow and brown show the different times that the book may have been written:
"In the present translation of Leviticus only the main sources have been separated from one another, viz. (1) the Law of Holiness, which has many distinguishing features (colored YELLOW); (2) the main body of and laws (UNCOLORED); and (3) a few laws, which may for several reasons be regarded as later in origin than P (colored BROWN). [p. 58]

Included in the introductory notes is this:
"The monstrous form Jehovah (which is a combination of the consonants of JHVH with the vowels of the Hebrew word for Lord, Adonai) was first introduced by a Franciscan Friar, PETRUS GALATINUS, in 1516 A.D." [p. viii]