How to change the color of the text on the input box (which appears by default in value attribute) in HTML form?

Question

I'm not talking of the INPUT TEXT rather the text that appears on the input box by default, inside the VALUE attribute.

<input type="name" value="this text color I want to change">

How can I change the colour of this text to grey and keeping the entered text black(this is actually what I'm trying to do)?
Please someone help!

Sorry for the messy question, I framed it the best way I could.