WorkAlpha has two very good articles on resume color and resume white space, both written by Megan Koehler, an expert resume writer.
In her articles, Megan Koehler suggests using color in your resume to give it a distinctive touch. However, color should only be used to accentuate important aspects of your resume and not become a distraction. As for white space, it should be used to enhance the readability of your resume.
Making subtle changes to your resume to add color and adjust the ratio of white space versus text can definitely improve its visual appeal.