The Color of Magic

Each school of magic has its own color, and typically manifests in that way. Different traditions may supercede or affect this: a sorcerer of a white dragon bloodline might have everything themed as white ice and snowflakes lightly tinted in the color appropriate to the spell; a wizard of the Purple Order might have everything appear in patterns of shades of purple solely.

Abjuration - purple

Conjuration - white

Divination - blue

Enchantment - yellow

Evocation - orange

Illusion - red

Necromancy - green

Transmutation - indigo

The source of magic has something to say about the patterns and shapes of the magic's manifestation. That is to say, abjuration spells cast by a sorcerer might take the form of lilac purple 3d ectoplasmic shapes interposing themselves between the caster and the danger; a cleric of Zhako might manifest elegant shields of bright silver decorated with patterns of purple like amethysts; an abjurer wizard might summon into existence complex geometric patterns with runes scattered across the nexi, which flash and vanish.