On the left hand side of the robot there are two cables: from the limit switch (3 wires)...

...and one from the stepper motor (4 wires).

Connect the limit switch wire to the X- limit switch pin with ONE extension cable. Note the red wire from the limit switch is on the left. Make sure your extension cable does not reverse this connection or the robot may not turn on.

Using your previous notes, connect the stepper motor wire to the left stepper driver with an extension cable. Note the blue wire from the stepper is on the left. Make sure your extension cable does not reverse this connection or the motor will turn backwards.

There will be more 3 wire extension cables left. Connect them all in a line to the pen holder, making sure to match the colors. The pen holder wire is yellow brown red. connect the red wire of the pen holder to the black wire of the extension.