In ETABS 2013 and later versions, mode shapes can be found via Tables>Analysis> Results>displacements>Diaphragm center of mass displacementsTables > ANALYSIS RESULTS > Joint Output > Displacements > Table: Diaphragm Center Of Mass Displacements.
Make sure modal results are available , and that load cases including modes is selected (as a default modal results are excluded)and Modal Load case is selected. This can be verified/changed by right clicking on tables>modify options changed by Display > Show Tables and click on Set Load Cases button as shown below:
