I'm not sure what current the Arduino 5v pin can supply (not an i/o pin)... if it's enough (and I can't see that this page says what it is) then you could use that 5v as the power to the motor thru the transistor per your sketch, with the i/o pin switching the transistor.
Some one in the last day or three posted what the 5v pin's current is, iirc, but I don't know who or in what thread.
(Edit- Your original post spoke of the 40mA from an I/O pin, which is not the same as the 5v pin....)