Aim to understand it rather than memorize it. Break it down and it's less daunting than looking at several graphs all at once. If you understand the physiology and basic physics (pressure and volume loops) of how the heart works, then you can understand the diagram.
There's probably some good YouTube videos out there that explain it well if you're stuck.
I agree with Ismet wholeheartedly. You need to understand the physiology behind this graph to answer questions on boards or school exams. There are some things in cardiology where you can just straight memorize the info (like the buzz words for the cardiac murmurs; I just posted a video on Youtube called "How to Memorize Heart Murmurs with the Memory Palace") but some things you really do need to have a basic understanding of. In fact, in that video I listed five concepts that people really need to understand, perfect for reviewing with a study group, and #1 was:
1. What happens to the pressures in the four chambers of the heart with each murmur?
It won't be daunting once you realize how predictable the cardiac cycle is and I bet you'll actually feel a great sense of ownership once you get to the point where you understand this graph well enough to draw it on your own without having memorized anything.
Electrical signals on the EKG -> muscle contractions -> atrial/ventricular pressure -> opening/closing of valves + sounds
muscle contractions also -> ventricular volume
-> means affects (directly)
The aorta part should be obvious