Colors impact your listener on a subconscious level. Whether considering a color scheme for your slides or the tones you will wear to present, we must be mindful of how colors impact others in all aspects of our presentation.
Check out these two presentations on color psychology:
http://www.slideshare.net/spikhaleel/colour-psychology
http://www.slideshare.net/ImagineDesign/introduction-to-color-psycology