Word for someone who loves bright colours

There is no single word to refer to such a person. But you could get plenty of adjectives to refer to bright clothes, so you may use them appropriately in the sentence you want. Some of the adjectives:

• garish
• gaudy
• vibrant
• electric

The first two words are depreciative, the latter ones are rather descriptive. Your sentence could be:

He shows a preference for vibrant colours.

I think this is best described as Colourful or Flamboyant?

Chromatophilia is sometimes used for love of colour generally (alongside, e.g., melanophilia, xanthophilia, leukophilia as love of black, yellow, white, respectively), but doesn't emphasize bright colours in particular.

Augophilia, by contrast, is the love of bright lights, glare, or sunlight. So, it includes light, rather than just bright or glaring colour.

Maybe someone with sufficient Greek can suggest some coupling of the two ...