How to I manage my quantity product by colour and size?

Example,

Dress 001
Red - Size: S - 5pcs, M - 4pcs, L - 2pcs
Black - Size: S - 3pcs, M - 2pcs, L - 1pcs

Dress 002
Green - Size: S - 7pcs, M - 5pcs, L - 8pcs
White - Size: S - 5pcs, M - 2pcs, L - 4pcs

In my Attribute Manager, I have changed my dresses with colours and sizes. But how can I associate quantity by colours and size in one product page? The product page only allow me to add overall quantity. It does not make sense if a dress has 2 colours and 3 sizes but only 1 quantity in a page