Could she be a Buff Orpington/Dominique cross?
She looks just like my Buff Orpington/Barred Rock cross pullets, except for the rose comb.  Some of my pullets of this cross had blue slate legs (like your hen), others had yellow, others had white, and others had willow green.  It puzzled me and a lot of other people but I finally found out from an online chart that the rooster (a hatchery Buff Orpington) must of been impure for leg color.