#Mathematica 89 bytes

    r@i_:=StringReplace[i,#->" "]&/@(Complement[y,#]&/@Subsequences[y=Characters@i])//Column

     


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**Explanation**



`i` refers to the input string

`Subsequences[y=Characters@i]` returns all subsequences (represented lists of characters) of the input. (`Subsequences` was introduced in v. 10.0.4)

For each subsequence, `Complement...` returns those characters from the input string that are **not** present.  Each of those characters is replaced by an empty space via `StringReplace[i,#->" "]`.

`Column` displays the results in a single column. Each output string has the same number of characters, resulting in aligned letters. 





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    r@"abcdefgh"

[![output][1]][1]


  [1]: https://i.sstatic.net/u5o5Y.png