Take a look at how they were birthed. They were the 100 children of Sky and Earth. These parents alone can give you insight as to what they can produce. Snakes also represent a close affinity with the Earth.
However, those were merely the newest Roman versions. In the earlier Greek classical sources, they were depicted as looking like men, wearing armour, and having incredible strength (that didn't stop increasing unless they were in contact with their mother the Earth [Gaia]).
I don't like the snake-legged depictions, it seems a bit inhumane. You, however, can pick what you so wish.
Have a blessed day/night.