Sub Maybe()
Dim c As Range
For Each c In Range("A1:D12")    '<---- Change Range as required
    With c
        Select Case .Interior.Color
            Case Is = vbRed
                c.Value = -1
                    Case Is = vbGreen
                        c.Value = 1
                    Case Is = vbYellow
                c.Value = 0
            Case Else
        End Select
    End With
Next c
End Sub

Sub ShowColour()
    Dim RGBColour As String, R As Integer, G As Integer, B As Integer, c As Range
        RGBColour = Right("000000" & Hex(Selection.Interior.Color), 6)
            R = WorksheetFunction.Hex2Dec(Right(RGBColour, 2))
            G = WorksheetFunction.Hex2Dec(Mid(RGBColour, 3, 2))
            B = WorksheetFunction.Hex2Dec(Left(RGBColour, 2))
        MsgBox "RGB(" & R & ", " & G & ", " & B & ")"
End Sub

Sub Maybe_With_RGB()
Dim c As Range
For Each c In Range("A1:D12")    '<----- Change to actual used colored range
    With c
        Select Case .Interior.Color
            Case Is = RGB(255, 0, 0)    '<----- Change to what you get for Red
                c.Value = -1
                    Case Is = RGB(0, 255, 0)    '<----- Change to what you get for Green
                        c.Value = 1
                    Case Is = RGB(255, 255, 0)    '<----- Change to what you get for Yellow
                c.Value = 0
            Case Else
        End Select
    End With
Next c
End Sub