Why do transition elements show coloured complexes

we know that transition elements have vacant d orbital.Vacant d orbital consists of 5 equal energy levels .So when a light falls on it ,the unpaired electron present on it gets excited and it is transferred to the vacant d orbital of same energy level and some unpaired electron also gets transferred to higher energy level above d orbital.When it returns back to its original level it releases energy in the form of light whose wavelength is in the visible region