First, the apparent size of the saturated region is largest in the DSS image. Second, the density of outlying stars is greatest in the same image. This is due in part to the relatively short 7.8 second exposure time. You can peer farther into the cluster core because it is less saturated than in the optical images. It is because thermal infrared emission at these longer wavelengths is normally a product of dust and young stars.
Globular clusters have no young stars and very little dust.
Hence, there is no source of far-IR light associated with M77. Globular clusters contain primarily older and redder stars, and hence are most impressive at the visible wavelengths that our eyes can see. The red areas in the image center may be weak radio emission from the cluster core. The green and blue blobs are random electronic noise, similar to static, introduced into the radio receiver. The environment of globular clusters is essentially devoid of strong magnetic fields and fast-traveling electrons, and therefore we should not expect significant synchrotron emission from M79.