Taking all her toys away is a massive over reaction. And what if she misbehaves again after you have taken all her toys away - what are you going to do then?
Asking her to improve her behaviour is far too woolly and vague - she will have no idea what you mean, you have to specify particular behaviours or you are setting her up to fail.
Is she naughty at home or only at the CM's? Is it after school when she is tired? (I was an after school club supervisor - you get to know what each child needs when they come out of school or you will get poor behaviour because often they can't articulate their needs - they have just done a day at 'work' they need to wind down. So it might be food, a chat,a story, quiet time on their own, a good run round the field - its different for all children.)
Your child minder should be dealing with the bad behaviour as it specifically arises, and telling your DD what she expects and then most important praising her when she manages it. Does she ever say anything nice about your DD? - If I was your DD I would really hate going somewhere that ended everyday with a moan to my mother about how awful I'd been and ignored anything nice or helpful I'd done. I'd soon start to think there was no point in trying to be good.
Rather than threaten a punishment long after the event give your DD something to aim for a specific thing you want her to do/address - (not a big huge vague thing) and get the CM to tell you if she achieves this, then praise her for her efforts, tell her how pleased you are with her for trying (and don't set up perfection as the standard by which she succeeds or fails, have trying hard as the standard) No one can be perfect in their behaviour all the time, especially if they are tired, or with people/other children they may not especially like, they can only try and hopefully learn to self correct if they stray off the track. And with five year olds each day is a new day - don't hark back to previous misdemeanors - they can't remember then.
I would actually worry about a CM who cannot manage to get a five year old to listen and do as she is told, she's effectively telling you she can't do her job.