In standard usage, 象 and 像 are distinct kanji with different meanings. In particular, they are rarely confused in the following contexts:
- 象 (ぞう; elephant): 象牙 (ivory)
- 像 (ぞう; statue): 銅像 (bronze statue)
However, these kanji are also often associated with "image":
- 象 (しょう; image): 現象 (phenomenon), 印象 (impression), 抽象 (abstraction), 具象 (embodiment)
- 像 (ぞう; image): 現像 (development of film), 映像 (movie)
In such cases, 象 and 像 were not strictly distinguished in the past. For example, if you search the 青空文庫全文検索, you will find that older authors sometimes used 実象, 映象, 群象, etc., which would be considered mere typos in modern standard usage but were accepted variants at the time. In your specific case, it's safe to consider 図象 as a synonym for 図像, so it's "亜-shaped icon".
(I doubt this is a "typo". Although 常用字解 seems to be a relatively recent book, I suppose the author intentionally chose 図象 based on some historical or academic background. Old notations tend to be preserved in the context of historical researches.)
Please also read dROOOze's answere here: How does ayakashi, あやかし = 妖 or 罔像?