Dressing in the right attire for an interview shows that you're serious about the job, respectful of the interviewer's time, and are genuinely interested in the position. It also shows that you have done enough research to have an understanding of the corporate culture, and leaves the impression that you are someone who would fit easily into the workplace dynamic.
The best colors are Neutral colors, navy, gray, black, and brown for a job interview. White is also an excellent color for a blouse or button-down shirt.