It comes with a wiring harness already attached, so there's not much wiring it yourself on the board end. There's a diagram on the sales page for the board by itself, but it's tiny. It used to be bigger.
https://ultrasabers.com/product/obsidian-usb-soundboard/Though, you can e-mail customer service and they can get you the info you need, if it doesn't come with a diagram.