This is not a flowchart. A flowchart is defined as; a graphic representation, using symbols interconnected with lines, of the successive steps in a procedure or system. The word cannot be used interchangeably with diagram. A more appropriate alternate ward would have been a descriptive chart or outline. These are actual synonyms for a diagram. Be careful with word choices. One incorrect choice can alter the focus of the discussion and cause a failing paragraph score.
There are not enough information within the diagram to warrant a 4 paragraph set-up. This is only a 3 paragraph design. The summary and overview should have been blended into one paragraph. Single sentence presentations are not acceptable as paragraph presentations. It will not geta helpful score.
It is not advisable to say
Looking at the graph
because the assumption is that the report is detailed enough to be understood without needing to look directly at the image. Always frame these as factual descriptive reports. Do not refer the reader to the image for any reason.
First, cacao trees are grown in S.America, Africa and Indonesia which bear the ripe cacao pods.
Good information, bad sentence structure. What was the problem? There was no need to start with "first" because the topic sentence did not need it. There was no point in using that format since there was no second or third reference. Use a uniform ordinal next time.