Colors in scans can be a problem because of software issues. You may be able to tweak settings or switch software to improve matters. I've got a procedure I follow with my software (
VueScan) that works for me.
Grain may be exaggerated in scans because of
grain aliasing. This is a somewhat controversial topic, but the basic idea is that the random pattern of grain (or, technically, dye clouds in color film) interacts with the highly regular pixel pattern of a scanner to exaggerate the appearance of grain in scans. With my Minolta DiMAGE Scan Elite 5400 at 2700 dpi, I usually see this in color films of ISO 400 and faster. The effect can be reduced by scanning at higher resolutions. There are also post-scanning grain-reduction algorithms, but in my experience they tend to create slightly blurry images.