Are you referring the paged navigation below the slideshow? These are left aligned by default to work with any slideshow quantity and dimensions.
But you can change the position to center them for your own slideshow where you know the quantity and width. You just need to take a screenshot of your site and measure how wide the paged buttons are, subtract that from your slideshow width and divide by two. Then you can change the left position of the paged buttons. Like if the buttons are 20px wide and the slideshow is 400px wide, set "left" to "190px" like this: