Vintage 80s abstract bright geometric wrap dress

Amazing 80s (?) brightly colored geometric abstract wrap dress with side ties. Please see photo where back seam has pulled a bit. I'm not sure if the "S" marked on the tag is a laundry mark or a size but please see measurements which seem to correspond with a size small. Approximate measurements: 19" underarm to underarm 18.5" hips, flat, at widest 32.25" back neck to hem