Hi Mike
There are numerous styles (like the ones I distribute via FormFonts) that have a pencil look. They are typically monochromatic. If you are handy with Photoshop (or other editors) you could probably merge a pencil-styled export with a colour version of the same drawing to achieve a coloured pencil look. If you are interested in a monochromatic look - in a single colour other than a graphite one - then again you could manipulate (photoshop etc) a graphite-styled render to look like it was drawn using one coloured pencil.
I attach another way. An image was exported from SketchUp. It was then processed with the PhotoShop-compatible filter from LittleInkPot called 'Sketcher'. The result (monochromatic) was then merged with a copy of the original export to produce a pencil crayon effect. The 'Sketcher' plugin is worth the money in my opinion. Sorry but it is for Windows only. http://www.littleinkpot.co.uk/
Regards, Ross
pencil-crayon-example.jpg