Ok so this is a bit of a different grid than what a normal one looks like.
I have appointed the coordinates to their respective places on the line.
Where the pink dot is, would be where your XY line goes (0, -4) the blue is where your YZ line would go (4, -1) and the green is where your ZX would go (6, -3).
Remember the four quadrants!
Quadrant 1 - The top right quadrant - Both points positive
Quadrant 2 - The top left quadrant - X-coordinate is negative while the Y- coordinate is positive
Quadrant 3 - The bottom left quadrant - both points are negative
Quadrant 4 - The bottom right quadrant - The opposite of Quadrant 2 which is; X-coordinate is positive while the Y-coordinate is negative.