button.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<style>
    #body {
        width: 100vw;
        height: 100vh;
        background-color: rgb(134, 134, 241);
    }
    
    #click {
        position: absolute;
        top: 50%;
        left: 50%;
        color: rgb(8, 8, 8);
        background-color: rgb(57, 226, 35);
    }
</style>

<body>
    <button id="click" onclick="myFunction">Click Me</button>
    <script>
        var colors = ["blue", "green", "gray", "yellow", "black", "red", "pink", "white"], // the color choices Blue, green, grey, yellow, black, red, pink, white
            index = 0; // index of the current color

        document.getElementById("click").onclick = function() {
            document.body.style.background = colors[index]; // set the color of body to the current color
            index = (index + 1) % colors.length; // increment index to point to the next color (if it goes beyond the length of the coices array get it back to 0 using the modulo %)
        }
    </script>
</body>

</html>