I thought to compile all Intel HD Graphic Drivers links since they are needed for all generations. We had older generations direct download earlier but it seems not updated. I have sorted them according to Generation and Operating System type.
Intel HD 15.40.28.4501 (5th/6th Gen) *Listed on front-page but old Driver listed
Windows 7/8/10 x64/x86
https://downloadcenter.intel.com/download/26228/ - Updated on 12/08/2016
Intel HD 15.36.31.4414 (4th Gen)
Windows 7/8 x64/x86
https://downloadcenter.intel.com/download/25978/ - Updated on 13/05/2016
Intel HD 15.40.28.4501 (4th Gen)
Windows 10 x64/x86
https://downloadcenter.intel.com/download/26229/ - Updated on 12/08/2016
Intel HD 15.33.43.4425 (3rd Gen)
Windows 7/8/10 x64/x86
https://downloadcenter.intel.com/download/25977/ - Updated on 13/05/2016
Intel HD 15.28.24.4229 (2nd Gen) Windows 7/8 x86
https://downloadcenter.intel.com/download/24970 - Updated on 05/06/2016
Intel HD 15.28.24.64.4229 (2nd Gen) Windows 7/8 x64
https://downloadcenter.intel.com/download/24971 - Updated on 05/06/2016