Form field link color

I'm assuming you mean in the notification emails. Styling HTML emails is something that is difficult because there are so many inconsistencies between mail clients. Some actually override link color rules but you can try including an style block with a declaration.

<style type="text/css">
a {color:#ff0000}
</style>

Here's some more info on styling HTML emails

http://www.campaignmonitor.com/css/

http://articles.sitepoint.com/article/code-html-email-newsletters

http://thinkvitamin.com/design/html-emails-taming-the-beast/