Electrons leave tracks in the track detector and an (often quite big) energy deposition in the EM-calorimeter. Remember that the track and the calorimeter deposition should be coloured with a bright shade since the electron is a charged particle.
Positrons look like electrons, the only difference is that the tracks of the positrons are curved in the other direction compared to tracks of electrons. When we use WIRED we do not have to distinguish between electrons and positrons.
As with electrons, photons leave a deposition in the EM-calorimeter, but since they are neutral particles they do not generate any tracks in the track detectors. The energy depositions in the EM-calorimeter have a dark shade if they are due to photons.
The key to identify electrons, positrons and photons is to look for energy depositions in the EM-calorimeter.