As someone who has sold POS systems for years, I can tell you there are many systems better than the one tied to QB.
IN fact, there is one I used to sell for about $ 800 that is now free.
And it has what you need. It's called a "matrix" or "grid". Think of it as a spreadsheet with sizes down the rows and colors across the columns. This is how salepeople take orders for soft goods, either on the phone, at shows or in your place of business. It's how they think. Bath linens or tee shirts, it's how to track soft goods.
Anyhow, this program has a built in matrix setup, (they call it a template) where you enter 5170 one time and then apply the sizes and colors and when you go to sell a 5170 you are prompted for the size and color.
And it will export your daily sales to QB if you want. I always dicouraged this, as it's just a simple "cash receipt" entry per day to enter your sales into QB, but the export is available if you want to use it. That is basically how the QB POS add-on works, it's really not QB, but an add-on POS system they chose to use.
Here's a link -
Welcome to POSitive Software Company - POSitive Free POS