It's not really possible to get the same look as seeing colored shadows through glass, but you can fake it a bit:
1. Assign a normal glass material to your shower glass - hide it from camera.
2. Duplicate the shower glass object and make it just slightly larger than the original object - the idea is just to avoid overlapping of geometry.
3. Assign a typical AGS material to this object. To make some reflections on it, have rough (99) BSDF and add a second BSDF, or a second Layer with a BSDF and set the roughness low, or 0. This will be your shiny layer. Set this second Layer to Additive to avoid too much darkening on the final look of the AGS.
By playing with the Layer opacities of this AGS material you can get some acceptable results. For example, comparing real glass with this approach:
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