do you want it to go over the pillows? with a tuck? what size drop? i think you should attack your bed with a tape measure before you go any further.
if you want the kitties to be centered on the bed and the pillow part to be solid, then all it needs is border color on the top - a lot of it, to cover the entire pillow with tuck underneath and behind (against the headboard). also, again f you want the kitties on top, all you need is borders on the sides. if you enlarge the entire quilt, the cats will be hanging over the edge. was that the look you wanted?
the queen bed is 80" long with approximately 22" covered with pillow. so deduct that amount. now you have 56" to work with if you want the entire picture to lay flat on the center of the bed. that's the size of the pattern as it is, right? the bed is 60" wide. the quilt pattern is 56. again, a perfect fit. are you sure you want to change it?
you may want to border the central design in 9-patches in the same or coordinating colors, as is found in the pattern. or try something that you find more appealing. maybe applique little cats around the border.