I had mine done years ago as part of a redundancy package to help me find another job. There were four in the group and that helped because you could see the effects on the others as well as yourself.
It wasn't just colours, it was textures, patterns and styles too. Our body shape was identified with suggestions and tips for choosing clothes.
We got a great little wallet that is about the size of a credit card wallet. It contains fabric swatches of all the recommended colours, textures and patterns. I carried it in my bag for years.
The only problem was black and navy were not recommended for me and my business wardrobe was based around them! I did use the advice though because overall I thought it was excellent.
I still use the basics from that consultation and dread to think what the consultant was charging. I'd get a recommendation from someone who has had their colours done and you admire their style. It needs a good eye.
I know a lot of companies use the scarf approach, but personally I think this can look a bit obvious if you don't learn to do it well.