Is there a formal way to describe three word color adjectives?
They are called 叠词(Reduplication). Many 叠词 work as adjectives or adverbs, but you may well see them in other places. There are many forms of 叠词, yours is just one of them:

ABB: 绿油油, 红彤彤, 美滋滋(Not a color)
AAB: 飘飘然, 呱呱叫
ABA: 越来越, 看一看
AABB: 白白净净, 欢欢喜喜
AABC: 鼎鼎大名, 苦苦相逼
ABAB: 考虑考虑, 研究研究
ABAC: 美轮美奂, 载歌载舞

There may be other forms but I can't think of them by now.
So for ABB and color only, there are no specific terms, but you can describe it as ABB结构的描述颜色的叠词.