There's a lot of rules about what you can and can't do. But if you're confronted with an otherworldly, unfathomable ancient entity of unknowable and incomprehensible desires, then it is definitely okay to cry.
But also, you can just cry if you want to. Crying is good for the body, and good for the soul.
When we cry in response to stress, tears contain a number of stress hormones and other chemicals. It is believed that crying reduces these chemicals, and thereby helps alleviate stress. Crying may have a direct, self-soothing effect as well. Crying activates the parasympathetic nervous system (PNS), which helps people relax.