At this time we do not have a conversion chart. Cups is a volume measurement while grams is a weight and varies for each ingredient.
If it helps...a cup is about the size of a large apple. One half cup fits in the palm of your hand. Once cup of leafy greens is about 1-2 handfuls depending on size of hand.
While it's not ideal, this link may give you an idea of some various ingredient conversions: http://allrecipes.com/howto/cup-to-gram-conversions/