The dev.exe is in the same directory as the normal .exe....
If you are talking about Rebellion, then you got it through steam and therefore will have to go through that file location to find the game....games are in steamapps (or something like that)....
Anyway, technically "developer" does not appear in the files name, only "dev"....if the name of the normal .exe is "The Cat in the Hat.exe" then the dev.exe has the name "The Cat in the Hat Dev.exe"....
I don't remember the exact name of the normal .exe since I don't have an install to look at right now otherwise I'd give you an exact file location...