A graphic ephemeris shows planetary movement over time. On the vertical axis you have degrees – usually 45° – and on the horizontal axis you have time.
As planets move forward in the zodiac you get a diagonal line from top left to bottom right across the graph. Any retrograde periods can be seen as the line moves up the graph. The steeper the line, the faster the planet moves although you will need to consider what time period your graphic ephemeris is for. Very slow moving planets can draw almost horizontal lines.
45° – the most common value used – will show all conjunctions, squares, oppositions, semi-squares and sesquiquadrates where lines cross. If you look at the 10° line on a 45° graphic ephemeris you will see any planets which are at 10° cardinal and 25° fixed.
Other ranges can be used. For instance 30° will show positions in a sign, 72° will show quintile relationships and you can also look at 360° to see the whole zodiac.
Depending on the amount of time you are considering you may choose to look at just the slower moving planets. The Moon moves so fast that you would only use it over short periods of time.