Yes, you can use RS-485 transceivers supplied by different voltages on the same network. There should be no compatibility issues. This is because the transmitter output voltages of the one transceiver is compatible with the receiver input voltages of the other transceiver up to the common mode voltage range specification. For example, MAX3070 and MAX3080 can be used on the same network even though the former is supplied by 3.3V and the latter is supplied by 5V, as long as the difference in maximum data rate is taken into consideration.