Hi Tom,
I would create an Rdata file that contains all the data, and a function that you can use to retrieve the graph you want. The graphs can be in some nested named list, grouped by the groups, type of question, etc., in an organization that is most logical for you. The retrieving function could be created with something like this:
get_graph <- (function() {
env <- new.env()
load("my-data-file-with-all-graphs.Rdata", envir=env)
function(group, at, question) { env[["allgraphs"]][[group]][[at]][[question]] }
})()
and then you can get your desired graph via get_graph(group="foo", at=1, question="advice").
The advantage of not using the list directly is that if you change the data format, file name, etc. you don't need to update the code. You can also make the retrieving function more flexible, e.g. to retrieve all time points for a question and group, etc.
The advantage of the closure trick (i.e. to return a function that will return the data, and then call it immediately) will make sure that you only load the file once from the disk, and that the object itself is hidden.
Best,
Gabor