True, but official artwork and in-game character art shows Iris with silver-ish blonde hair color. The artwork shown in the loading screen is mostly fanart-like in sense, some of the loading screens has Iris with the same silver-ish blonde hair color like her and one of player character fighting side by side against monsters with other players in the background. And the little skit with her alone walking with monsters following behind in a chibi-like sense.
There's a good portion where I've seen her with purple, pink, and I recall seeing one with orange tint in her hair but mostly it's the silver-ish white color. Also isn't there an in-game Fashion Set costume that makes up Iris Livier's appearance that female characters can wear which has her hair silver-ish white? Heck I could've swore in the prologue chapter of the MMO that Iris has the same silver-ish white hair.
She's an "anime" character, true, but most anime characters when finalized have an official color scheme to help the readers/players/fans to recognize their character. Hopefully I'll find out soon.
"Invoke... VIRUS SOUL!!!" ~ From my VirusChris manga project