Direct proportionality refers to a linear relationship between two variables, where one variable increases or decreases at a constant rate as the other variable increases or decreases. A graph that shows direct proportionality would be a straight line that passes through the origin (0,0). If the graph is not a straight line, or if it does not pass through the origin, then it is not directly proportional.
In the graph you have provided, y is not directly proportional to x because it is not a straight line. This can be seen by the fact that the line on the graph has a curve to it, rather than being a straight line.