The atomic-scale structures of liquid Si, Ge and Sn have been modelled by the reverse Monte Carlo method. A geometrical analysis of the model atomic configurations has been carried out in terms of bond angle distributions and spherical harmonics invariants. Similar geometrical features, including signatures of local tetrahedral order, have been found in the first coordination shells of all the liquid metals studied. A relation between the local atomic ordering in liquid Si, Ge and Sn, and that of the corresponding solids with the tetrahedral white-tin-type structure has been established. The influence of the local and medium-range atomic orderings in liquid Se, Ge and Sn on the shape of the respective structure factors has been discussed.