1550s, "figure of speech," from Medieval Latin schema "shape, figure, form, appearance; figure of speech; posture in dancing," from Greek skhema (genitive skhematos) "figure, appearance, the nature of a thing," related to skhein "to get," and ekhein "to have, hold; be in a given state or condition," from PIE root *segh- "to hold."
The sense "program of action" first is attested 1640s. Unfavorable overtones (selfish, devious) began to creep in early 18c. Meaning "complex unity of coordinated component elements" is from 1736. Color scheme is attested from 1884.
"devise a scheme," 1767 (earlier "reduce to a scheme," 1716), from scheme (n.). Related: Schemed; scheming.