If you are not happy with the default design of the AD FS Sign-In page you can use the commands below to update the page. Below are a few of the commands that i have used to customize the page but other options are available.
Default Sign-in Page:
Change Company Name
You can change the company name with the following powershell command:
Set-AdfsGlobalWebContent -CompanyName "New Company Name"
Change Company Logo
When changing the company logo Microsoft recommends the dimensions for the logo to be 260x35 @96 dpi with a file size no larger than 10KB.
Set-AdfsWebTheme -TargetName default -Logo @{path"c:\images\logo.png"}
Change Graphic on the left
To change the image on the left you can use the following powershell cmdlet. Microsoft recommends that the illustration be 1420x1080 @96 dpi and no larger than 200KB.
Set-AdfsWebTheme -TargetName default -Illustration @{path="c:\images\illustration.png"}
Add a description to sign-in page
You can use the following powershell command to change the description on the sign in page. The text for "signInPageDescriptionText" paramter supports html tags.
Set-AdfsGlobalWebContent -SignInPageDescriptionText "For assistance please visit our support site here.
"
Additional Resources:
https://technet.microsoft.com/en-us/library/dn280950.aspx
