How to use Collect to group negative terms?

Test example:

SeedRandom[0];
poly = FromDigits[RandomInteger[{-5, 5}, 10], x]

(*  1 - 5 x + 3 x^2 + x^8 (2 + 5 x) + x^4 (-4 - 3 x + (3 - 5 x) x^2)  *)

The problem is that if you separate the added and subtracted terms, when it is evaluated, the minus sign is automatically distributed and the terms sorted (since Plus has the Attribute Orderless).

1 + 3 x^2 + 3 x^6 + 2 x^8 + 5 x^9 - (5 x^7 + 3 x^5 + 4 x^4 + 5 x)

(*  1 - 5 x + 3 x^2 - 4 x^4 - 3 x^5 + 3 x^6 - 5 x^7 + 2 x^8 + 5 x^9  *)

For output formatting: You can prevent Plus from being evaluated and sorting the monomials. This is inconvenient for further computation — I would just let the polynomial be reordered. However, for making a human-readable presentation, it can be done with Defer or HoldForm. Here is one way:

Plus @@ KeyValueMap[
  # /. {False -> #2, True -> -Defer@Evaluate[-#2]} &,
  Total /@ GroupBy[MonomialList[poly], Internal`SyntacticNegativeQ]
  ]

(*  1 + 3 x^2 + 3 x^6 + 2 x^8 + 5 x^9 - (5 x + 4 x^4 + 3 x^5 + 5 x^7)  *)