Colman is a city in Moody County, South Dakota, United States. The population was 634 at the 2020 census. Colman was first named Alleā¦Colman is a city in Moody County, South Dakota, United States. The population was 634 at the 2020 census. Colman was first named Allentown, and under the latter name got its start in 1890, following construction of the Milwaukee Railroad through the territory.