The phrase "nice color contrast" refers to the visual effect created when two colors are placed next to each other in such a way that they create an appealing combination. Full definition
Just the right amount of spice, and a garnish of cilantro and shallots provide nice color contrast to the yellow broth. (weheartfood.com)
A dusting of powdered sugar gives them an (un) seasonally appropriate finish (ha, ha, ha, yes this everlasting winter is very funny) and provides nice color contrast to the shades of beige underneath. (lapechefraiche.com)
I would especially encourage serve over black or red rice for a nice color contrast. (hummusapien.com)