Separator in layout panel?

Is there a separator or method to make one in the layout panel? As my layers multiply, I’d like to have a quick visual defining groups of layers.

Or if not a separator, a way to change the text color of layer names in the the layout panel.

you can define sublayers by rightclick on a layer or the icon above the layers

drag n drop works too in case you already have many layers

Thanks. I was aware of the sub layers, I was just hoping for a way to visually define groups via a separator and/or colors. Oh well.