Here is a bit of inside information on how to get the theme png
https://kuler.adobe.com/api/v2/themes/<abcdef>.png , just replace <abcedef> with the theme id. You can easly get the themeid by looking at the theme URL in info view
Yes, you can get the theme PNG with a URL, as Shamit suggests. You can take a screenshot, or if you are using the iOS app, you can share an image of the theme via email.