Femtosecond time-resolved experiments on chemical and biophysical electron-transfer systems may reveal complicated coherent beating which often cannot be simply attributed to nuclear motion on a single Born-Oppenheimer potential-energy surface but rather reflects electronic transitions driven by coherent nuclear motion. To facilitate an intuitive classical interpretation of these experiments, a recently proposed theoretical formulation is employed that affords an exact mapping of discrete electronic states onto continuous degrees of freedom and therefore provides a well-defined classical limit of a nonadiabatically coupled system. The formulation is used to consider the classical periodic orbits of an electron-transfer system, i.e., trajectories that describe periodic nuclear motion on several coupled potential-energy surfaces. Employing concepts of semiclassical periodic-orbit theory, it is demonstrated that transient oscillations observed in electron-transfer femtosecond experiments may be explained in terms of a few classical trajectories.