Override the color attribute of the shaders applied to the objects in your collection.
By default, when you add an object to a collection, only its transform node is included. If you override an attribute on the shader applied to the object, a shader subcollection is then created automatically for you.
To begin this example, Mesh_Killamari_Body has a blinn7 (orange color) applied, and Mesh_Killamari_Eyes has a phong1 (green color) applied. A render layer Minion_body has been created, with a collection named Killamari.
To override the color of the squid's body and eyes
Select a shader node; for example, blinn7 to display its Attribute Editor.
Middle-mouse drag and drop the Color attribute from the shader Attribute Editor to the Property Editor.
A Killamari_shaders collection is created, as well as a corresponding color override.
You can drag the Color attribute from any shader. You are only dragging the Color attribute, not the attribute of the blinn7 shader in particular.
Select the color override and set your new color values using the color swatch.
The color override will be applied to all objects (and instances of objects) that are in the same layer and that have either the blinn7 and phong1 shader assigned initially.