I think you'll get closest to the same graphics on the xbox at medium settings, then make sure you change the following.
Well I do know the xbox360 version does not use the large textures- so switch it to medium.
I think the actual game resolution on the 360 is 720p (if output is set to 1080p then it is just upconverting but not actually rendering at the higher resolution) so set resolution to 1280x720.
I am also pretty sure the xbox360 version does "bloom" filter effects rather than HDR.
You'll also want to pull back the view distance sliders about 20% of their default value.