There is an in-game option to select the colour of an object you want to built before you built it, this way you can ‘bulk’ built objects with the same colour instead of changing them one-by-one afterwards.
Select the main menu item of the object you want to built in the building menu
Right mouse click on the object you want to built in the first selection menu
Select the colour you want for the objects, please note that all objects from that menu will have the same colour
Select the object you want to built