Here is a generic manual from S&W's website. It will have general information about safety, etc., but it is not specific to your 1950s vintage Highway Patrolman. Still, if you want information on how to load it, unload it, clean it, handle it safely, etc., this should be helpful.
http://snwcdnprod.azureedge.net/site...l_12-15-16.pdf
If you want more in-depth information such as disassembly / reassembly etc., Amazon has Jerry Kuhnhausen's book, but that may be overkill for your needs and it is a hardcopy of the book, not a pdf. Not to mention it costs about $44 new: