Your table is more complex than you originally described. Try:

Sub Test()
Dim oCell As Cell
Dim lngIndex As Long
lngIndex = 1
For Each oCell In ActiveDocument.Tables(1).Range.Cells
If oCell.Range.Information(wdEndOfRangeColumnNumber) = 7 Then
If lngIndex = 4 Then lngIndex = 1
Select Case lngIndex
Case 1: oCell.Shading.BackgroundPatternColor = wdColorBlue
Case 2: oCell.Shading.BackgroundPatternColor = wdColorBrightGreen
Case 3: oCell.Shading.BackgroundPatternColor = wdColorLightYellow
End Select
lngIndex = lngIndex + 1
End If
Next
End Sub