You said you like the icons on that screenshot, so I posted a link where you can find thousands of icons like those. You find something you like and save to your desktop and then save it to the icons folder with iPhoneBrowser.
Now if you don't want to have to bother doing any of that, I recommend using the Illumine theme. It's available in Cydia and includes more icons than any other theme I know of. And if an icon isn't included, it will theme it for you. It will always be a white light at the bottom (rather than the colored lights that are on the icons that are included with the theme), but they match rather than standing out like sore thumbs and you don't have to do any of the work!
That's the one I'm currently using, here's a screenshot