How does Updike in A&P reveal the different personalities of each of the three girls?

The perception of the girls in John Updike's short story, "A & P" is that of the rebellious and romantic nineteen-year-old named Sammy, who is the first-person narrator.  As such, Sammy is a subjective narrator, and this subjectivity is certainly apparent in his infatuated description of the girl that he calls "Queenie," whom he finds sensually attractive with her

straps pushed off and...nothing between the top of the suit and the top of her head except just her.

Another way in which the girls' personalities are revealed is through their actions. That all three of the girls are, like many teens, proud of their sensuality is evident in their awareness of Sammy's attention to them.  Although they are somewhat self-conscious about this attention, they are also thrilled by his watching them:

She [Queenie] came down a little hard on her heels, as if she didn't walk in her barefeet that much, putting down her heels and then letting the weight move along to her toes as if she was tesing the floor...putting a little deliberate extra action into it....you got the idea she had talked the other two into coming in here with her, and now she was showing them how to do it, walk slow and hold yourself straight....

She must have felt in the corner of her eye me and over my shoulder stokesie in the second slot watching, but she didn't tip....She kept her eyes moving across the racks, and stopped, and turned so slow it made my stomach rub the inside of my apron, and buzzed to the other two, who kind of huddled against her for relief....the fat one with the tan sort of fumbled with the cookies, but on second thought she put the package back.

After they parade around the store some, they ask McMahon something.  Sammy says that McMahon pats his mouth, "sizing up their joints."  In his infatuation with Queenie, Sammy's carnal desire satisfies him aesthetically as well: "Poor kids, I began to feel sorry for them, they couldn't help it."

Despite their apprehension of Sammy's and the other men's attentions, the girls do not appreciate Sammy's quixotic act of chivalry and rebellion as he quits his job.  For, when he goes outside, the girls have departed.