  We study exclusive dijet production in coherent diffractive processes in deep
inelastic scattering and real (and virtual) photon-hadron ($\gamma^{(*)}$-h)
collisions in the Color Glass Condensate formalism at leading order. We show
that the diffractive dijet cross section is sensitive to the color-dipole
orientation in the transverse plane, and is a good probe of possible
correlations between the $q\bar{q}$-dipole transverse separation vector $\r$
and the dipole impact parameter $\b$. We also investigate the diffractive dijet
azimuthal angle correlations and $t$-distributions in $\gamma^{(*)}$-h
collisions and show that they are sensitive to gluon saturation effects in the
small-$x$ region. In particular, we show that the $t$-distribution of
diffractive dijet photo-production off a proton target exhibits a dip-type
structure in the saturation region. This effect is similar to diffractive
vector meson production. Besides, at variance with the inclusive case, the
effect of saturation leads to stronger azimuthal correlations between the jets.
