Every spellcaster has their own color; it is not based on their alignment or type of magic or anything. It is mostly a matter of choice or personality, though most clerics tend to clump into the same general color if they worship the same gods because they tend to choose the same colors and/or have similar personalities.

Elan has a similar color to the Azurite priests because it's not as if everyone in the North sits around going, "Gosh, we can't pick blue, because those people on another continent all picked blue!" Tsukiko uses the same color for her divine magic as the Azurite priests because they both worship the Twelve Gods, who are worshipped as a pantheon by all alignments in Azure City.

And as far as the girl in #730, I promise that whether she is using mind energy or fire does not affect the story in the slightest, and therefore it doesn't matter whether or not you can tell what it is.