Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Caitlyn is super powerful mid to late game. I recommend focusing more with building attack damage than attack speed because she needs to get more damage output than attacks per second. If you want attack speed I recommend building items that have attack speed and attack damage like the two that I put into my build.