An is sitting on a throne with a staff of office. On his head is a helmet with six horns done in the traditional Sumerian style rather than the turned in Akkadian style. I gave An white hair to imply his age.
An is the god of heaven, so I placed a cloud in the image. He is above this cloud to imply that he is the god of the upper heaven rather than a god of the air specifically. The seven star pattern is associated with An because he is the father of both Enlil and Enki, and others, and the grandfather of many more. This makes him the senior member of the council of seven gods who decree fate.
The seven star pattern is obviously both a celestial and a holy symbol. The seven stars in this pattern represent the seven who decree fate. Stars in an asterisk like form are also traditional symbols of divinity. The dingir symbol itself is even a stylized star.
The name d|An is traditional, but there is something lost in translation. The Sumerians wrote a single symbol before the names of the gods to denote their holy status. This symbol was not pronounced when one said the name. It was just there as an identifier. When translated into English it became tradition to place a lower case d and a line before the name.
He has a white staff to differentiate him from other gods most notably Enlil.
It is important to note however that in traditional Sumerian representations one draws power from that which one stands on. For this reason An might be better depicted with his throne sitting on stars rather than clouds.