It's simply proper (but slightly misunderstood!) English.

There's a little known rule to how adjectives are ordered in English:

1. Quantity or number.
2. Quality or opinion.
3. Size.
4. Age.
5. Shape.
6. Color.
7. Proper adjective (often nationality, other place of origin, or material)
8. Purpose or qualifier.

Dead is "Quality or Opinion".

Yellow is "Color".

Going by these rules, quality comes before color, so it should be "Dead Yellow Coral", while currently it is "Yellow Dead Coral".

Therefore, it should be "Dead <Color> Coral", instead of "<Color> Dead Coral." It just kinda sounds wrong in English.