Think aperture and shutter speed does not affect the colours much.
Think the following does have some effect though:
ISO - higher ISO affects the contrast of the colours according to an article I read in a magazine.
Lens - Some lens gives a warmer color while others a cooler color but the overall colour variation should be consistent with the lens used.
Model used - different mode used on the camera gives different colour and saturation. It is the same as doing it on PS just that the camera does it for you. Think if shoot in raw, there is no difference.
White Balance - Think this one is quite standard. A wrong WB gives a wrong colour. Though there's nothing as a really "wrong" WB since if the end result gives the right mood then it's good.
Think thats about all I know. Maybe wrong somewhere.
it's generally accepted that if you shoot film, you should overexpose (either opening up or slowing down) to get better contrast and tonality.
for digital it's a little trickier.. but from experience i would still say that the above is still true to some extent.
so to answer the question, yes, overexposing somewhat CAN LEAD to more contrasty and saturated images. it doesn't mean that you will get it instantly.
Opps the master have spoken, didnt read what he have said. Can I say that, by deliberately overexposing and under exposing, we are actually trying to either preserve the highlight (over) or shadows (under) so that when we PS we can get the effects we wanted? But in the process we will have to loss some of the dynamic range?
ps to jOhO: Like your photos very much, hope to be able to shoot with my style one day too