I thought there wouldn't be one:
https://www.cinemablend.com/news/1550940/why-warcraft-will-never-have-a-directors-cut-according-to-duncan-jonesLooking further, it is probably reasonable to assume that the 40 minute longer version is a rough incomplete version without finished visual effects / CGI.
Further statements by the director (same thread):
"For those asking, no extended cut, that Im aware of. Lots of extra scenes on DVD though. There will be no directors cut. Just not possible."https://twitter.com/ManMadeMoon/status/758818614656937987"I am the director. I am telling you, there will BE NO DIRECTORS CUT. Got it?"https://twitter.com/ManMadeMoon/status/758855325785001984"no idea if therell be EXTENDED cut. Not up to me. Studio decision. What I KNOW there won't be is a directors cut."https://twitter.com/ManMadeMoon/status/767954123908124672"there can be no directors cut, because the footage necessary does not exist."https://twitter.com/ManMadeMoon/status/768329690725613569