A sample space is supposed to include all possible outcomes.
Using curly brackets to enclose this space and round brackets to show the results of throwing the die unlimited times until 6 is thrown we have:
{ (6), (1,6), (2,6), (3,6), (4,6), (5,6)
(1,1,6), (1,2,6), (1,3,6), ...
(2,1,6), (2,2,6), (2,3,6), ...
...
(5,1,6), (5,2,6), (5,3,6), ...
(1,1,1,6), (1,1,2,6), (1,1,3,6), ...
...
(5,5,1,6), ..., (5,5,5,6),
...}