I can't tell if strRng is a Range or a String.
I can't tell if the User is Selecting 1 cell or several.
This code, (which might not work,) is based on the User only Selecting one cell at a time.
Option Explicit
Private Sub Worksheet_SelectionChange(ByVal Target As Excel.Range)
Dim SelectionRange As Range
Set SelectionRange = Range("A:A") 'assign as needed
If Target.Count <> 1 Then Exit Sub
If Not Intersect(Target, SelectionRange) Is Nothing Then
ActiveSheet.Shapes.Range(Target.Text).Fill.ForeColor.ObjectThemeColor = msoThemeColorAccent2
End If
End Sub