Flags and probability

Mr. Jawkar was carrying with him flags of 40 countries and 40 labels of the corresponding country names. He wanted Mr. Anthony’s family to help him correctly assign labels to the country flags. He equally divided the flags and labels (at random) amongst the 4 family members of Mr. Anthony. He told them to put labels on the flags assigned to each of them but they were not allowed to exchange flags or labels with each other. What is the probability that all 40 flags get correct labels?