Ryan Hinchcliffe's early try put Giants ahead but Ben Roberts, Jake Webster and Mike McMeeken crossed in response to put Tigers 16-4 ahead at the break.
Gale and Adam Milner extended the lead before Ryan Brierley hit back.
Two more tries from Gale in a 24-point contribution and a Monaghan treble followed as Tigers dominated.
While Lee Gaskell added a further consolation try for Huddersfield in the second half, it did little more than add a semblance of respectability to the scoreline as they became the latest club to suffer a heavy loss at the Jungle.
Castleford have scored at least 43 points in each of their first four home games in Super League this season.
However, they were left to bemoan a series of handling errors after Hinchcliffe's try put Huddersfield ahead.
That was before Roberts scooped up a neat grubber kick by Gale to help put the hosts ahead after 21 minutes.
Huddersfield then saw their restart go out on the full, allowing Roberts the chance to quickly play provider for Webster as Tigers piled the points on.
Gale gave Daryl Powell's side the ideal start to the second half, crossing for the first of his tries after just 30 seconds, as Castleford went on to win big to remain top.
They are level on points with Leeds Rhinos, who beat Wigan 26-18 in Friday's other Super League game.
Castleford Tigers: Hardaker; Monaghan, Webster, Shenton, Eden; Roberts, Gale; Sene-Lefao, McShane, Moors, Millington, McMeeken, Milner.
Replacements: Cook, Springer, Chase, Holmes.
Huddersfield Giants: McIntosh; McGillvary, Cudjoe, Mellor, Ormsby; Gaskell, Brierley; Ikahihifo, Hinchcliffe, Wakeman, Ta'ai, Ferguson, Clough.
Replacements: Rapira, Leeming, Smith, Dickinson.
Referee: Richard Kendall
Luke Gale and Joel Monaghan both scored second-half hat-tricks as Super League leaders Castleford Tigers thumped strugglers Huddersfield Giants.