Representative array configuration files for Cycles 1 and after are linked to from the "CASA Simulator and Configuration Files" section of the Tools page in the ALMA Science Portal.

Configuration files for Cycle 0 are available from the Cycle 0 Documentation page. 

However, for convenience, some configuration files are available in several versions of CASA. The location of the files in a given CASA installation can be found using this command at the CASA prompt (also accessed through the inline help for the CASA tasks simobserve and simalma):

os.getenv('CASAPATH').split(' ')[0] + '/data/alma/simmos/'