I don't think there is an option for doing that, so if you really want it, you'll have to modify the Org mode sources and carry the patch privately (I doubt very much that this change would be accepted upstream). That means that every time that you want to update, you will have to apply the patch again (and again, and again...)
The patch itself is simple:
diff --git a/lisp/org-habit.el b/lisp/org-habit.el
index f76f0f213..5f2e11518 100644
@@ -430,6 +430,8 @@ current time."
(while (not (eobp))
(let ((habit (get-text-property (point) 'org-habit-p)))
+ (insert-before-markers "\n")
(move-to-column org-habit-graph-column t)
(delete-char (min (+ 1 org-habit-preceding-days
It just adds two lines to the function
org-habit.el and since this function is only called when the agenda is created, it is a fairly safe change.
But as I said, you will have to carry the patch in perpetuity or fork the Org mode sources to create your own. Whether that's worth the bother is up to you to decide.
There are options to reposition the graph on the line and make it shorter or longer: as @gregoryg points out in a comment, you can change the position of the graph by customizing
org-habit-graph-column; you can change the length of the graph by customizing