No, you won't be penalised for not copying the diagram. However, it is strongly recommended that you do copy the diagram because you may have to add some labels on it. The marker can see very easily on a copied diagram what you labelled and will provide a higher level of clarity (remember you keep the exam paper, so any labels on the exam paper will not be seen by the marker, which is why you should copy the diagram if you want them to see what you've marked/labelled)