There is no classic Lewis dot diagram for C3H6. The diagram is unusual. Et first, all angles in Carbon atoms are tetrahedral. Second, the molecule C3H6 is planar. Angles between Carbon atoms are 60 degrees.Two of electrons of each Carbon atoms are bonds with two Hydrogen electrons.
3 x 2 = 6 Hydrogen atoms. Rest of two electrons of one Carbon atom are verticaly in direction to one of two Carbon atoms to made single sigma connection. This is reapited in triangle. So there is no torsion stress between all bond in molecule C3H6 as Theory predict.