1. A system construction assistance apparatus, comprising: a first display screen; a second display screen; and a processing section that displays, on the first display screen, a plurality of units each belonging to one of a plurality of categories such that the units are sorted by category, receives a first input to select one unit from the units displayed on the first display screen, generates a system configuration diagram on a basis of the received first input, and displays the generated system configuration diagram on the second display screen, wherein, after a first input is newly received and before a next first input is received, the processing section predicts a category to which a unit to be selected by the next first input belongs on a basis of a plurality of first inputs received in a past and presents the predicted category as a candidate category to a user.