Very often items look very different in the preview window to how they render.  I suggest applying the material to the hair and then render it and see if it looks okay.

If it still doesn't appeal to your aesthetic ideal for the render then post screenshots of your material room settings and your render settings and I'm sure someone here will know.

I would have loaded the hair and had a look for you but I am in Cloth Room Sim Hell at the moment ;o)