Here, let me give you an example, if you want a different directory than /home, you need to specify -d /path/to/home as well. So:
root@redmine:~# mkdir /mytestusergroup
root@redmine:~# useradd -m -s /bin/bash -d /mytestusergroup/testuserian testuserian
root@redmine:~# ls /mytestusergroup/
testuserian
root@redmine:~# ls /home/ | grep testuserian
root@redmine:~# cat /etc/passwd | grep testuser
testuserian:x:1001:1001::/mytestusergroup/testuserian:/bin/bash
First I create /mytestusergroup as this is the directory I want the home directory, second I use the -m to create home directory and -d to change from default of /home/username, then I check in mytestusergroup directory and you can see home is created, and last I check under /home to see if it was create here, and no it wasn’t - to prove that the command I gave works. And lastly, I check /etc/passwd to show it created exactly as my command.