As much as you want to, don't give them the middle finger and do what you want. Since you submitted it to review and they rejected it, they have proof that you were told your plan was not acceptable. You should take the approach that NMAS suggests and point out that the current color is green and was apparently ok, so why isn't it ok now? If they still say no, then it's going to be a matter of how much do you want to pay to get your way? You're going to have to lawyer up and then figure out how hard you want to fight to keep it the current color.
You will have much better luck trying to work with them than against them. I don't know the Florida laws, but in many states, the HOA has the right to correct a violation and charge you for the work. If you refuse to pay they can put a lien in the property and even foreclose. Sorry to bring the bad news.