Unlike R 3 , the homogeneous spaces E(−1, τ ) have a great variety of entire vertical minimal graphs. In this paper we explore conditions which guarantees that a minimal surface in E(−1, τ ) is such a graph. More specifically: we introduce the definition of a generalized slab in E(−1, τ ) and prove that a properly immersed minimal surface of finite topology inside such a slab region has multi-graph ends. Moreover, when the surface is embedded, the ends are graphs. When the surface is embedded and simply connected, it is an entire graph.