What kind of symbols for the polytheism?

Polytheism should not be thought of as a single, monolithic faith with just one identifiable symbol or tradition. Different polytheistic cultures have had different symbols, and at different times. The same symbols are often associated with monotheistic religions.

The ancient Egyptians used the fish symbol now identified with Christianity. They also used a symbol that looks like a cross with a bow - also sometimes associated with Christianity.

Followers of the sun god Apollo depicted him with a halo - based on the sun disc behind his head, often with rays emanating out. This symbol entered Buddhism via Greek influence, and is also used in Christianity.