Seen from the Sun, every planet goes round on a nearly circular ellipse, the inner ones faster. Seen from Earth, we are riding on one of those circles ourselves, so each planet's path is its own orbit minus ours. The result is a looping curve (the old astronomers' epicycles): each small loop is a stretch of retrograde motion, when Earth overtakes an outer planet, or an inner planet overtakes Earth, and the planet seems to move backwards against the stars. Along the zodiac shows the same thing as we see it in the sky: position along the ecliptic (the Sun's yearly path) across the page, with east to the left as when you face south from India, and the retrograde stretches drawn thicker.
Planet pair joins two planets with a straight line at every step. Because orbital periods come in near-whole-number ratios, the lines build up a rosette. Earth and Venus return to almost the same arrangement every 8 years (13 Venus orbits, 5 close approaches), which draws a five-petalled figure; Jupiter and Saturn line up every 19.9 years, three times round, which draws a triangle-like pattern over 60 years.
Positions come from the VSOP87 theory (and a dedicated model for Pluto) in the astronomy-engine library, computed in your browser and projected onto the plane of Earth's orbit (the ecliptic of J2000). Geocentric positions here are geometric, without light-time or aberration, which changes nothing visible at this scale. Sizes of the planets are not to scale.