Oh boy. Okay, let me preface my response here with a definition of what I believe, since labels are not working here. I'm sure that I will fall under different labels from differrent people too.
I believe in an energy of sorts that permeates through all life. This is what I refer to as both Source and Divine interchangably. This Source is the essence of life, the spirit/soul. It is what makes up the link between and within all existence. I am as much connected and a part of other people, as trees and plant life, as the water flowing through the land and the life within it, as the animals grazing on the land, which is also permeated by this energy. It flows through and is a part of everything. My thought of spirit can best be equivocated to a wave on the ocean. It is a singular wave, with its own power and force, but is a part of the rest of the ocean and therefore connected to all other waves. It eventually falls and returns to the general energy of the ocean until energy rises up again and produces another wave. So is reincarnation. Energy is never ending, only forever changing.
Since everyone's spirit encounters different experiences and accumulates different knowledge, it is all lended to the Source as a whole. One can "tap into" the Divine nature of this and pull from the experience and knowledge of all. In order for some to try to communicate with the whole Source, which is overwhelming, it becomes easier for humans to visualize a simpler form, a manifestation of sorts, of this energy. Our own spirit and mind help create the manifestation of the attributes that we most want to associate with. Whether apparition happens or not depends on the spirit, the willingness of the mind to actually see something, or if the person really feels it's necessary to see something. I don't believe in it being a "god" really, but the energy prevalent in life that some conceptualize and need/want to be their "god/gods".
Thusly, visualizations of "god" are whatever is most accepted or easy to connect with for the person visualizing. Personally I visualize a man and a woman, younger, about 25 to 35 in appearance. Parental and loving. They have no distinct or definite faces or specific form though. The feeling and knowledge I receive is more important than the appearance of what cannot be wholly fathomed anyway.