Style matters in Yourdan notation and can be used by the analyst to provide additional meaning to the DFDs. The size and shape of bubbles are up to the diagram creator and their client. Curved or straight arrows can be used. A diagram looks neater with one or the other but not both in the same process. There is no excuse for hand-drawn diagrams today except during a white-boarding stage.
The analyst may choose to name the processes for the role that performs them, as well as use colors to differentiate the types of entities or flows in the diagrams. With all of these style options the DFDs can provide as much or as little detail as is needed to appropriately represent the process for the given audience.