The CSS property color controls the text color in elements generically. In your case, to change the color on hover, use the :hover specifier;

input[type = "submit"]:hover {
    color: #FF0000;
    //you can add more styles to be applied on hover
}

Note that you can as well specify the color using the rgb(x, y, z) format. Here's a little demo to illustrate: little link. You can play around with the demo and view the source here: another little link.

I hope that helped!