More information at this old post:
The cards we see match up pretty well with the stuff the kids yelled out.
My take is that this wasn't a requirement. All the card could have been the exact same color and the children could have still ordered different favors. When the children announced which favors they wish, Chapel handed them a colored card that was reasonable close to the selection.
When that one kid wanted to reorder, Chapel could have simply used the same card the kid used the first time, but choose to employ a different card.
As noted above, there was the element of a game to it.