You can look through a telescope and the actual light from the stars will be hitting your retinas, so you can answer this question for yourself! For most thing

You can look through a telescope and the actual light from the stars will be hitting your retinas, so you can answer this question for yourself! For most things like nebula and galaxies the shapes can be made out easily but often the colors are absent or muted because our eyes' color cones don't do as well in low-light as a monochromatic rods. This is similar to how if you have ever seen the aurora the colors are hard to perceive but if you use a camera they pop out a lot more. There's a big range though and it depends on the intensity of light from the object. There are certainly nebulas and other objects out there with enough light intensity that our eyes can naturally perceive the color. The other thing to keep in mind is that people's night vision and ability to perceive color in low light is highly variable, much like how our visual acuity (near/far sightedness) vary greatly by individual and worsen somewhat with age.