In QGIS, set your colour scheme for your first image (so in your case, Features 1 and 4 being only visible). When you add a map to composer (by clicking the "Add new map" option), you should see your thematic map. Export as an image or pdf etc.
Next, go back to QGIS and change the colour scheme of the same layer so that Features 2 and 3 are visible. Go back to Composer and select Item Properties in the menu window (right-hand side usually) and click the Update preview. Your map should be updated with the new colours. Export this as an image, pdf etc.
Hope this helps.
