use your imagination. use one of the 6 button slagcoin layouts and it shouldnt be too much difficulty to lay out the 7th button.
let me ask, do you have a digital caliper? if not, get one. a caliper will allow you to measure center to center exactly how far apart you want your buttons to be, and wherever from the center of a button you want your next button to be, you can go in a complete circle and place it there. thats how i did my layout, although i usually use the caliper for measuring electronics connectors i need,
it also worked great for my cp layout.