Typically, the 'nick' field that is returned back from the user.json/[kloutid] endpoint can be used to build the profile URL.
Profiles URLs are in the format of: http://klout.com/user/[nick]
This will be true of users you've looked up by Twitter or Google+.
Alternatively, you can use the kloutId directly, but it's not preferred: http://klout.com/user/id/[kloutId]