I'm replying to your question from home, and don't have all of my usual resources for checking. I'll attach a .pdf example of questions 47 and 48 to show how I would most likely show these graphs. I would extend all of the arrowheads outside of the graphing area (since they extend to iinfinity anyway), so that the reader can easily discern the difference and they are not confused with the grid lines. Does it say elsewhere in the text what the significance is of colour for each of the 2 arrows? I would use a dashed line for the grid -- it should be the least significant part of the graph. I would make the x- and y-axis a lesser line strength then the coloured arrows. I would also use different arrowheads than the axis arrows -- again to assist in distinguishing them. I would use a very light pin prick to show the intersecting shaded area. I suggest that you also check with Dorothy under the Math section of the forum.
Hope this makes sense and that you find these are helpful!