Nevermind I found it, I wanted to edit KingdomUnlimitedImprovements.xml found in \data\English\Core Improvements, it was simple enough, I just had to find

        <TileDesign>K_Air_Shrine_01</TileDesign>

and change it to

        <TileDesign>F_Air_Shrine_02</TileDesign>

Then to make sure the icons and construction graphics match up I changed the following.

<ConstructionTileDesign>K_Air_Shrine_Build_01</ConstructionTileDesign>

to

<ConstructionTileDesign>F_Air_Shrine_Build_02</ConstructionTileDesign>

I haven't tested yet but that should do it if anyone else wants to.