ElseIf Color = "Orange" Or Color = "Purple" Or Color = "Yellow" Then

Or you could also use a Case Statement

Select Case Color
Case "Red"
   Debug.Print "Do This"
Case "Blue"
   Debug.Print "Do That"
Case "Orange", "Purple", "Yellow"
   Debug.Print "Do the other thing"
Case Else
   Debug.Print "Do the last thing"
End Select

IF color = "Red" then
   ' do stuff
ELSEIF color = "Orange" OR color = "Purple" OR color = "Yellow"
   ' do other stuff
ELSE
   ' do default stuff
END IF

Personally, though I would probably:
1. use a CASE statement
or
2. create a lookup table that contains the color and the name of the subform
and then perform a lookup to retrieve the name of the form to open based on
the color.
or
3. use arrays in a similar fashion to #2
or
4. if the user is picking a color use a two column combo box that contains
the color in one column and the formname in a second hidden column