You are setting the color of the paragraph the link resides in, but in style.css (that is part of the theme you are using) there is a rule targeting all <a> elements that is more specific targeting and is overriding the color you are trying to set at the <p> level.
You can try customizing the theme by adding additional CSS rules to override the hyperlink color. I would not edit style.css in the event the theme gets updated and overwrites any changes you make.