You can check the workflow graph by clicking on any of the workflow on workfow page and then clicking on graph page as shown in above tutorial
The workflow execution graph shows the static graph of the workflow where each rectangle represents the tasks and the edges represent the execution order of each tasks, where a edge from one node to another node represent the connection from one task to another task.
Graph of the workflow can be viewed on the execution page of that particular workflow.
The rectangles represent the task and the edges represent the connection between nodes, so the edge from one task to another tells about the next task or step in the workflow after the current task is executed successfully.
The yellow color around the task means that the task is running and if it turns red that means it is in a failed state and workflow has failed and if it is green in color then it is executed successfully.
The dotted rectangle represents that the task is a conditional task and the highlighted border suggests which tasks were executed based on the condition defined in the workflow.
If there are multiple nested conditional tasks then on clicking the task that was executed, then clicking on the conditional task will open another nested condition and now there will be two dotted rectangles around tasks as seen in above tutorial and this will keep on increasing until the task are executed successfully and there are no nested conditions left.