The elements in the drawing are appropriate enough, so don't stress on that.
What I do see is that the Uno on the receiving side has no power going to it when it is unplugged. The power only seems to go to the servo. That may be an omission in your drawing, or it could be a problem.
Oh Yes, you are right! The drawing is not appropriate, sorry! I am using an Y cable because I wanted that the ESC provide the current to the Servo and UNO as well.
So the UNO and the servo share the same power supply provided by the ESC.
