The Store of effects, accessible from the Lab window, allows having your favorite effects in a common place and sorted by types if you wish (through different subfolders)
The effects files that are stored there in fact are standard image files in JPEG format containing the recipe of the effects. The difference with other saved images is that all the effects show a unique, common image so you can compare the different effects more easily.
You can change the that common image to any other of your choce:
Put in the main folder of the store of effects your image file in JPEG format and name that file _BaseImage (notice the initial character that is an underscore). From now on any effect you save will use this image.
If you create subfolders in the store of effects you could have "_BaseImages" specific for each subfolder.
You can rebuild the images in the Store of effects: In the lab mode, right click the button "Store of Effecs", you will have an option to "Rebuild Effects with BaseImage". This option has other suboptions that allow choosing if it will rebuild all the effects or from a particular subfolder.