What would the world look like if the human retina perceived radiation from gamma to radio waves?

The retina is not the main thing here. We see with the brain. The picture that is formed in a healthy mind and taken as reality is built by the brain. In Nature, initially there are no concepts of color or sound.

Think about why sound notes repeat by ear: do-re-mi-fa-sol-la-si -... ( and again ) ...- do- re-mi ..., while the frequency of the sound wave always strictly increases. That is, the brain assigns the same note to different frequencies.

The brain could work in much the same way with the eye. The colors of the rainbow (k-o-w-z-g-s-f), logically, should have continued further: red again ( purple is red plus blue ) and everything will start repeating in a circle as with sound. Unfortunately, the eye no longer perceives these frequencies of light and we will never know))

That is, according to this theory, the world would not change much for you if you saw in the range from radio waves to gamma radiation ( in terms of color), as it does not change much in the case of hearing loss during growing up (the range of audible frequencies narrows with age). The brain adapts.

Another point of view is that the brain can provide consciousness and additional colors. He already does this: black, brown and others are not in the rainbow and no frequencies correspond to them. There are multiple indications of persons (who took hallucinogens)) that they saw colors that did not exist in the ordinary state of consciousness. In principle, from the point of view of science, I do not see anything surprising in this version. Consciousness and the brain are still poorly understood.

Mother Evolution is extremely wise and gave us the most effective range of vision (sensitivity) of the electromagnetic spectrum of the Universe - the optical range from violet (wavelength, λ = 380 nm) to red (λ = 740 nm).

But the same Evolution gave us the brain and the ability for scientific activity, the result of which is giant ground-based optical, radio, gamma telescopes and extra-atmospheric spacecraft (for example, Hubble Space Telescope, Fermi-LAT Gamma Ray Space Telescope) chanting the Universe around the clock in the entire range of the electromagnetic spectrum of the Universe radiation.

To see the results of these studies, take a look here, where NASA provides an image of the Milky Way galaxy in the entire spectrum of electromagnetic radiation.