I read all salts from sodium salts form colorless solutions unless the anion is colored. Can someone explain?
There are various colors of chemical compounds because color is dependent on all of the interactions of all the components of the mixture, including the concentration. Some materials can appear to be one color in dilute solution, but a significantly different color in concentrated solution, because the level of absorption at a particular wavelength becomes so high that it dominates the color.
In the case of the sodium salts, it turns out that sodium ion does not have an electronic transition in the visible range, so it's invisible! However, all the other materials, ions, compounds, etc., may contribute their own absorptions to the mixture.