Graphene is in the focus of an immense scientific interest due to remarkable quantum properties which may emerge already at room temperature. We present here a study of electronic transport in single-layer graphene ribbons in three-terminal configuration set-ups, where the finite-size effects become of importance. These systems are characterized by much more complex stability diagrams than their nanotube (CNT) counterparts. A symmetry-related suppression of transmission of some states is responsible for the Fabry-Perot interference patterns obtained for CNT devices, whereas these dark states become conducting for graphene. This additional complexity is investigated by analizing shot noise properties.