You must ask them if the color that they are applying leaves a mass on your hair. If this is the case, you must not use it.
Also, you can apply any color except for black (or a color that looks like it).

I wanted to kno if i can color my hair from beauty salon any color except black. My question Is it okay to use the products they use to colour hair or its haram to colour hair using those products which are kind of permanent mostly it’s chemicals.does islam concern about the product u use or its only the look of the colour that matters? Please advice