Can matter waves be changed to a different 'color' the way light waves can?

Yes. Matter waves depend on the momentum of the particle, so that high momentum particle have shorter 'deBroglie waves' than low momentum particles. The exact equation for the wavelength of these waves is just

                     2
              E = m c

or            P = E/c       or   E = P c

( actually  the relativistic formula for non-zero restmass particles is
                2      2  2     2  4
               E    = P  c   + m  c

from which P = E/c

then
                              h c
since              E = ---------------
                          wavelength

you get
                                       h  c             h
                   wavelength  =   ------------    =  ------
                                       P  c             P

where h = Planck's constant = 6.6 x 10^-27. For an electron moving at 1000 cm/sec, P = 9.1 x 10^-28 x 1000 = 9.1 x 10^-25 gm cm/sec, and so its wavelength is 6.6 x 10^-28 / 9.1 x 10^-25 = 0.00072 centimeters. If it moves at 0.5 c, its wavelength becomes 2.4 x 10^-11 centimeters or 0.0024 Angstroms. So, you can change the 'color' of a particle by getting it to move faster. Even a stationary particle has a non-zero wavelength because of the relativistic formula for its total energy which includes its restmass. This gives an absolute minimum wavelength for the electron of P = 9.1 x 10^-28 x 3 x 10^10...and then 0.0012 Angstroms.
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