Looking for a transparent conductive spray/paint/ink
I don't know of any transparent conductive paints.  Have you considered using a piece of metal foil (possibly copper roofing foil from a Home Depot or Lowes) with a piece of veneer adhered to it.  The capacitive touch sense should still work through the veneer.

You can get all kinds of veneers at Woodcraft if you have a store local to you.

Link to Veneers at Woodcraft