If you are referring to concrete5 5.6 and not 5.7, the multilingual (aka internationalization) addon already jas an automated job that creates the multilingual sitemap.
BTW it must be activated:
edit your config/site.php file and add this line of code:
Once you have installed the multilingual package, in the automated jobs you'll have two jobs that create the sitemap. The "standard" one and the "multilingual" one. You should delete the former and keep the latter (otherwise you risk that the former job overwrites the sitemap generated by the latter job).

For the concrete5 5.7 series I've just proposed this change:https://github.com/concrete5/concrete5-5.7.0/pull/2369...

If the core team accepts it, it'll be included in the next release.

Hi
I have on 5.7 Multilingual Settings :
1. Attempt to use visitor's locale based on their browser information
2. Redirect home page to default locale.

On google webmaster I have setup property's
mysite.com/en
mysite.com/fr
How do we deal with this when google is asking for sitemap mysite.com/en/sitemap.xml when it exists in mysite.com/sitemap.xml

Thank you very much for the detailed replies. Yes, I'm on 5.7, so great that you proposed the change for the future, and too bad that functionality you mentioned in 5.6 wasn't carried over. In any case, it's not absolutely essential, but every little boost we can have in google helps.

Appreciate the feedback.