It is pretty straight-forward. You would use the BeforeSave workbook event to check all of the fields, and add colour where appropriate, not saving if any incompletes.
Something like
Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
Dim LastRow As Long
Dim vecColours As Variant
Dim fErrors As Boolean
Dim i As Long
Dim j As Long
vecColours = Array(xlColorIndexNone, 25, 28, 39, 40, 37) 'different colours for different columns
With Me.Worksheets("Master")
' handle dynamic number of projects
LastRow = .Cells(.Rows.Count, "A").End(xlUp).Row 'column A is server name
For i = 2 To LastRow
' clear it down first
.Range("A2").Resize(LastRow, 5).Interior.ColorIndex = xlcolorindexnon
' assume 5 columns of data
For j = 2 To 5
If .Cells(i, j).Value = "" Then
.Cells(i, j).Interior.ColorIndex = vecColours(j - (LBound(vecColours) + 1))
fErrors = True
End If
Next j
Next i
If fErrors Then
MsgBox "You have invalidate input"
Cancel = True
End If
End With
End Sub
To be more helpful, we would need more details.