Liberia, in West Africa, is not associated with a European power on this map. What is the reason for this?

I can't see the map, but I think I can answer the question anyway. Liberia was special in that it wasn't a typical colony of an European country: it wasn't established with a thought of integrating it into the country or extracting resources from it, as with the other colonies. Instead, it was thought of as a country for black people: freed slaves from the US.