If you have looked at most presentations and the diagrams, charts and tables the colours look very mis-matched in comparison to the coporate colours often used. Mainly this is because people either use the default Excel colours or they choose colours to (rightly) highlight differentiations, but it ends up looking like a rainbow.
If you look at many professional presentations, or better - annual reports. The first thing you will notics is the consistant colour schemes being used. As a quick tip for business professionals, don't worry too much about choosing colours - because they are already choosen for you to a large extent. The fastest way is to look at the corporate logo, adverts and other professional marketing colaterals that exist and they will dictate your colour scheme.Taking BP annual report slides as a good example, the logo being a shade of green thus dictates that all charts and diagrams will have similar colouring. You would also notice it only uses colours along the same hue (or variations of the same colour - lighter and darker). Using this quick tip will help standardise and produce more professional looking slides.