Change top menu categories with one click

Hi all,
Can you give me an advice, what to do to create four buttons and change with them a top menu categories.
The idea is to have 15 or 20 catefories, but to show only a part of them by default and when visitors click/over the button to hide those categories and to show others.
I use Super Mega Menu for my top menu and the version of opencart is 1.5.6.4.