  The X-ray colors and X-ray-to-optical luminosity ratios (L_X/L_B) of 61
early- type galaxies observed with the ROSAT PSPC are determined. The colors
indicate that the X-ray spectral properties of galaxies vary as a function of
L_X/L_B. The brightest X-ray galaxies have colors consistent with thermal
emission from hot gas with roughly the same metallicity of 50% solar. The
spatial variation of the colors indicates that the gas temperature in these
galaxies increases radially. Galaxies with medium L_X/L_B also have spectral
properties consistent with emission from hot gas. If a simple one-component
thermal model is assumed to describe the 0.1-2.0 keV X-ray emission in these
galaxies, then one possible explanation for the progressive decrease in L_X/L_B
among galaxies of this class could be the progressive decrease in metal
abundance of the X-ray emitting contained by the galaxies. Galaxies with the
lowest L_X/L_B values appear to be lacking a hot interstellar component. Their
X-ray colors are consistent with those derived from the bulges of the spiral
galaxies M31 and NGC1291. In M31 the X-ray emission is resolved into discrete
sources, and is apparently due primarily to low mass X-ray binaries (LMXBs). We
therefore suggest that the bulk of the X-ray emission in the faintest
ellipticals is also due to LMXBs. Previously, the X-ray spectra of X-ray faint
galaxies had been found to be described by a hard component which was
attributed to LMXB emission, and a very soft component of unknown origin. We
show that the very soft component also likely results from LMXBs, as a very
soft component is seen in the X-ray spectra of the nearby LMXB Her X-1 and
LMXBs in the bulge of M31. (Abridged)
