Wiki says, "Grey is its own complement." Grey can be cool. Grey can be warm. Grey can be neutral. Grey may denote collaboration or independence even. So, does grey symbolise ingenuity or simply a disorderly jumble...?
I think grey is perhaps one fine state of mind, whereby we strive to be mediatory, well-balanced and unflappable amidst uncertainties. Rainy days may stay, but it shall be clear sometime later.