Event-B is a formal method that supports correctness by construction in system modeling using stepwise refinement. However, it is difficult to understand the rigorous behaviors of models from Event-B specifications, such as the reachable state space or the possible sequences of events. This is because the Event-B model is described in a style that lists events that have concurrently been enabled depending on their guard conditions. This paper proposes a method that helps in understanding the rigorous behaviors of an Event-B model by creating an abstract state graph. The core of our method involves dividing the concrete state space by using the guard conditions of individual events to extract states that are essential to enable possible transitions to be understood. Moreover, we further divided the state space by using the guard conditions of events in the models before refinement to support understanding of changes in behaviors between the models before and after refinement. Our unique approach facilitated finding of invariants that were not specified but held, which were useful for validation.