My Arduino is heating up
The voltage regulator on the Arduino is designed to power the logic circuits, and perhaps a few LEDs and other digital devices. It is not designed to power 5 motors.

You haven't specified what current they draw - that is the important question, not the voltage.

As the comments under your question have said, you need to power the motors separately from the Arduino, not through it. However, connect the ground wires, and use the Arduino to control the signal wire to the servos.

The graphic below shows the general idea. For 5 servos even those batteries are probably not enough.

Notice that the power for the motor does not go through the Arduino.