It seems like what you have marked corresponds to the datasheet... Pin 2 is indeed ground, Pin 4 is Vin (5V), Pin 1(the orange line) is the Enable pin (which must be HIGH in order to start the converter), Pin 3 is the switch output, that goes directly to the inductor, the only pin that I'm not sure it corresponds is Pin 5 (feedback) which should be connected to the point between the inductor and the + of the capacitor (is the green one in your picture)... Figure out where goes that green one... If it goes to the + of the capacitor, then almost for sure, that is the part number...