For any given symmetrizable Cartan matrix C with a symmetrizer D, Gei\ss-Leclerc-Schr\"{o}er \cite{GLS14} introduced a generalized preprojective algebra Π(C,D). We study tilting modules and support τ-tilting modules for the generalized preprojective algebra Π(C,D) and show that there is a bijection between the set of all cofinite tilting ideals of Π(C,D) and the corresponding Weyl group W(C) provided that C has no component of Dynkin type. When C is of Dynkin type, we also establish a bijection between the set of all basic support τ-tilting Π(C,D)-modules and the corresponding Weyl group W(C). These results generalize the classification results of \cite{BIRS} and \cite{M} over classical preprojective algebras.