I'm not sure about purpose, but there are certainly atheists who argue that consciousness is part of the universe, so that there is both matter and mind. Prime example is Thomas Nagel, in his recent book 'Mind and Cosmos'. You would think that if you accept mind as a basic element, then mind would have intentions, but I will have to check Nagel. Of course, not all atheists are materialists or physicalists.
I think Nagel says that there may be a 'teleological principle' in the universe; well, I am no wiser, as I don't really know what means.