Here are registry files that apply Windows 8.1 Metro/UWP coloring styles that exactly match those known from beta versions of Windows, they cannot be achieved by changing personalization options in settings.
This changes both colors for the current users and when no user is logged in.
Save chosen one as .reg and apply:
Windows 8 Developer Preview green
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Accent]
"DefaultStartColor"=dword:ff386d0e
"DefaultAccentColor"=dword:ff51a110
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Accent]
"StartColor"=dword:ff386d0e
"AccentColor"=dword:ff51a110
Windows 8 Consumer Preview teal
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Accent]
"DefaultStartColor"=dword:ff504000
"DefaultAccentColor"=dword:ff878200
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Accent]
"StartColor"=dword:ff504000
"AccentColor"=dword:ff878200
Windows 10 Technical Preview blue
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Accent]
"DefaultStartColor"=dword:ff6d4a30
"DefaultAccentColor"=dword:ff8a6e59
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Accent]
"StartColor"=dword:ff6d4a30
"AccentColor"=dword:ff8a6e59
Note that the color format is ff meaning opacity and than BBGGRR so kind of reverse (you can set any color you want)
Does not work on Windows 8.0 (although Consumer Preview teal can be set in standard preferences idk about others)