Where to find wiring diagram for sears dishwasher model 587.1574590?

Sears Kenmore dishwashers beginning with 587 are actually manufactured by Frigidaire. You can find a bunch of manuals at:

http://www.frigidaire.com/support/ResultsPage.asp?strModel=587

Unfortunately, there is no exact match for your model number there, but in my case I was able to find a manual for a nearly identical washer with a similar model #.

You may also be interested in this product recall for some dishwashers with your model #:

http://www.cpsc.gov/cpscpub/prerel/prhtml93/93042.html