Senatorial or patrician calcei are a difficult animal when it comes to details. First, while there are representations in the form of statues and reliefs, there are no actual finds that would
tell us the cut of these. Then the literary sources are partly unclear and partly contradictory when it comes to color and the meaning of the different details encountered in said
representations. This is also due to the fact that these sources are spread across a couple of centuries, meaning that a) social rules around this type of
shoe may have changed between sources and/or b) that an author talking about something going on 3 or 4 centuries earlier may have been misinformed.
Goette suggests that the calceus senatorius only had one pair of corrigae (laces) while the calceus patricius had 2 pairs, but this is not 100% ascertained. Also there are references to people
other than senators wearing these shoes, e.g. those granted a triumph.
Below are pictures of my attempts of both a senatorial and a patrician pair of this type of shoes.
Goette, Hans Rupprecht: Muleus, Embas, Calceus. Ikonographische Studien zu römischem Schuhwerk.Jahrbuch des Deutschen Archäologischen Instituts
103, 1988. 401-64