A novel soybean cultivar designated S56-D7 with high yield potential, tolerance to Roundup herbicide, mid MG V maturity, and resistant to frogeye leaf spot (Cercospora sojina), southern stem canker (Diaporthe phaseolorum var. meridionalis) and races 1, 3, 9 and 14 of soybean cyst nematode, further including the plants and seeds of the cultivar S56-D7, methods for producing a soybean plant by crossing the cultivar S56-D7 with itself or another soybean plant. The invention also relates to soybean cultivar S56-D7 further comprising one or more single gene traits, and to methods of producing a soybean having such traits by transformation or mutagenesis. The invention also includes using the soybean cultivar S56-D7 to produce other soybean cultivars, breeding lines, and progeny