- Green-collar workers are those employed in the environmental sectors of the economy
- Pink-collar workers perform work said to be stereotypical women's work and are typically in the service industry
- Gold-collar workers who are classified into two: young, low-wage workers who invest in conspicuous luxury; or, highly-skilled knowledge workers, traditionally classified as white collar, but who have recently become essential enough to business operations as to warrant a new classification
Grey-collar workers often have associate degrees from a community college in a particular field. They are unlike blue-collar workers in that blue-collar workers can often be trained on the job within several weeks whereas grey-collar workers already have a specific skill set.
Anyway, there is still a lot in the color spectrum that hasn't been taken yet. Considering the ever-expanding range of worker-types, expect more color-workers to come out in the future.
Maybe I'll try calling one.
Source: Wikipedia