Okay, so you need to both color the cell below and also, reselect the cells that the user selected before running the macro.

If so, give this a try:

    Dim cel As Range
    Dim selectedRange As Range
    Dim preSelectedCells As String


    Set selectedRange = Application.Selection
    
    ' loop through the selected cells and fill the cells below it
    ' with a grey color
    For Each cel In selectedRange.Cells
        cel.Offset(1, 0).Interior.Color = RGB(220, 220, 220)
        
        ' keep a list of the cells the user had selected so they can be reselected
        preSelectedCells = preSelectedCells & cel.Address & ","
    Next cel
    
    ' move the trailing coma
    preSelectedCells = Left(preSelectedCells, Len(preSelectedCells) - 1)
    
    ' reselect the previously selected cells
    ActiveSheet.Range(preSelectedCells).Select