I would use MRIcroGL for this. Use Fill/Open to open your background channel, and File/AddOverlay to add your additional layers. In the Layers panel, you will see all your layers listed. You can click on the layer name to set properties (e.g. in the screenshot I have selected the `green` image and set its color scheme to `2green`). Note that each layer has a checkbox that toggles if it is visible (or drag the opacity slider for translucent). The Draw/DrawColor allows you to set your drawing color. Note you can toggle layers on or off to see the desired layer.