You can find the logs in /var/log/nginx/ location:
[root@ ~]# ls -lah /var/log/nginx/
total 608K
drwxr-xr-x 4 root root 4.0K Nov 11 04:36 .
drwxr-xr-x. 17 root root 4.0K Nov 11 02:10 ..
-rw-r----- 1 nobody adm 187K Nov 8 03:35 access.log
drwx--x--x 2 root root 267 Nov 7 04:45 domains
-rw-r-----...