You CAN NOT go by the color. Porsche sold the same antifreeze in both green and pink.
If there's a question, I would just flush the system and used one of the coolants suggested by Mike Focke's web page
http://mike.focke.googlepages.com/antifreezeforyourboxster
I use Pentosin Lifetime myself, but they're all the same if they're on that list.