You can customize the color of the prompt by using the comint-highlight-prompt variable. For e.g. I am using yellow foreground in my system. Here is how I have customized it by adding these lines in my ~/.emacs:
(copy-face 'default 'comint-highlight-prompt)In short, the first lines creates a font-face variable by copying the default face and the second line changes the foreground value of that font-face variable to "yellow".
(set-face-foreground 'comint-highlight-prompt "yellow")
Scott A. Kuhl's .emacs file helped me a lot in understanding how to customize this. Thanks to him.