Inspired by their own culture, Sintuilë's player decided to dress her champion first in a traditional Korean Hanbok-inspired outfit. Although it's a simple outfit that needs not much explaining, I think she got pretty close with the pieces available to her.
I've personally tried on that outfit, and found that a lavender dyed dress looked more like the picture of the real life hanbok. Now of course the hanbok has many variations in terms of colour, but I do like lavender more than the rose. Unfortunately, the dye costs 20+G in the Auction House so I don't Sintuilë is willing to spend that money on one dye.
Nonetheless, if you'd like to use this outfit, all you need are the same pieces, and you can almost mix and match any colour combination you like (though I think the hairstyle plays an integral part as well!) - just search "korean traditional dress" on Google and you'll get a vast selection of choices to follow that could suit any situation!
ps. I've been reminded to remind that despite it being Sintuile in game, it should be spelled Sintuilë, with the accent. It translates to "new spring" in Quenya which I can only guess is the player's real name :p
Shoulder: The Beast-keeper's Shoulder Pads (white);
Chest: Festive Azure Party Dress (rose).