As someone who has studied the history of Redwork and written three books on the subject, I can tell you that the color red was used only because it was more readily available than other colors and also because it was colorfast (color would not "run" when wet, fade in light, etc.)
Many other colors have been used since the inception of outline stitch embroidery, popularized in the 1880s by the Royal School of Needlework ladies. There is "Greenwork" and "Bluework" - made "early on" and later, after the turn of the century to the 20th c. : Yellow work, Pink work, Purple work, the use of variegated threads, etc. etc.
Quilters and embroiderers have always wanted to put their own spin on things, including using their own color choices (as threads became available to them). I say "go for it!" Please post a photo of your finished design! Good Luck!
Patricia Lynne Grace Cummings