I don't think files exist for that, you can check the WH40k pepakura wiki however that armor doesn't seem that complex, you'd probably be better building it out of EVA foam.
Well, I haven't seen much in the way of already made pep files for a Eldar guardian.. but perhaps I can help a bit.
I am in no way proficient enough with any modelling programs to dissect this model into just the required armor parts (and to do it in pep designer would take way too long)
BUUUTTTTTT if you want to do the work.. I ripped this model from DOW II: Retribution and converted it into a .pdo for you. It would be simple to pep if you could.. you know.. separate the armor parts from the model. If you need the .obj file let me know.