The color of the Hydrated copper (II) salts is

The copper present in the copper salts has unpaired electron so it can show color. Or due to the presence of Cu (II) ions.
Copper salts $\to$  Bluish Green 
Nickel salts  $\to$ Greenish Blue
Chromium salts  $\to$ Dark Green
Cobalt salts $\to$  Pinkish/purple
Manganese salts $\to$  Light pink
Ferrous salts$\to$   Light Green
Ferric salts $\to$  Pale Yellow