Hmm, well, if you're subbing I think they'll just be grateful to you for showing up! (Only sort of j/k here.)
I never shy away from wearing colour, pattern, texture, etc when working with children. Especially as a sub, it's nice if they have an easy way to identify/connect with you. If you wear hot pink, you'll probably be "Ms Hot Pink" the next time you teach. Kids notice and remember everything! I have preschoolers who question my footwear choices: "Are you sure those boots are warm enough?"
In a very conservative field, in a new position, I might hesitate to wear brights (or pastels, for that matter). But as others have said, I think silhouette and fabrication matter just as much, if not more.
From your description, it sounds like the bright pink will be anchored by a neutral (navy) so I think you're good to go!