Answer
Refer to the image below for the graph.
The interval notation equivalent of the given set is: $(-\infty, -3]$.
Work Step by Step
The given set covers the x-values that are less than or equal to $-3$.
This means that its graph will be the region to the left of, and including $-3$
To graph the set, plot a solid dot at $x=-3$ then shade the region to its left.
(refer to the attached image in the answer part for the graph)
The interval notation equivalent of the given set is $(-\infty, -3]$.