The About page for that mazegenerator site says it outputs SVG. So don't even need to import a PDF!
I've had some fun making maze-like and labyrinth-like images with Inkscape. It can be tedious, but is not hard by any stretch. Here's how I did it.
-- draw a square
-- duplicate the square
-- position is beside the first square (must use snapping for best result!
http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Snapping.html)
-- select both squares and duplicate
-- move those 2 into place
-- select all 4 and duplicate
-- etc., etc.
When you have a section that you want to keep, select all the squares, and do Path menu > Union. Magic!
Then just continue along. If you want the maze/labyrinth to be symmetrical, one or both ways, then you only need to construct one half or one fourth of it. Select the entire half or fourth and duplicate. Then flip either horizontal or vertical, as necessary.
Here's one that I made:
http://inkscapecommunity.com/ic_gallery/displayimage.php?album=42&pid=446#top_display_mediaI thought the color added another interesting dimension.