To accomplish that, you should make a copy of wp-login.php
and add the buttons yourself. With the help of JavaScript you could code something like this:
<p><button onclick="myFunction()">Administrator</button></p>
This creates a button.
<div id="myDIV">[email protected]</div>
And this is the text you want to change.
<script>
function myFunction() {
var x = document.getElementById("myDIV");
if (x.innerHTML === "[email protected]") {
x.innerHTML = "[email protected]";
} else {
x.innerHTML = "[email protected]";
}
}
</script>
Changing the text is possible with this script.
Another way of accomplishing this is by creating custom login links. I think this is going to be the easiest option for you. With a plugin like 'Autologin Links' (https://nl.wordpress.org/plugins/autologin-links/) you can create automatic login links for all users.
Connect the links, like this, to different buttons and you are ready to go.
<button onclick="window.location.href='/page1'">Superuser</button>
<button onclick="window.location.href='/page2'">Admin</button>
<button onclick="window.location.href='/page3'">Viewer</button>