I think you have to change your expectations to be honest. Some reception aged girls are very mature and sensible, many boys at this age are not. Personally I find "colouring-in" tediously boring, and am constantly surprised how much some children - especially girls aged 4-6 enjoy it! Most boys of this age do not, it's not unusual.
If you really can't cope with them, I would de-volunteer yourself. You may find it easier to help in a group which doesn't have your dd in it, as then you won't make comparisons.
However a few tips I would try:
Have really firm routines, and clear rules and boundaries, with consequences. LOADS of praise and encouragement. Get some stickers or stampers as rewards.
I would get some small mats to put on the floor and give them all one each to sit on. Each time you want to give them an instruction, or listen to a story they have to sit on their mats. Give a sticker to the child who is sitting nicely on their mat first. A third of the way into the story, stop, and say "Well done Harry, you are listening beautifully" or similar. Thank you Thomas for putting your hand up to answer the question, that's super, and is much better than everybody shouting out.
When you tell a story use puppets or toys or big pictures. Hand them out to the children as you tell the story.
Use lots of songs and action games and rhymes. Make sure they have opportunities to jump about a bit and use their bodies.
If they are being noisy when you need them to be quiet then start talking very quietly, don't allow yourself to get louder.
When they have a snack it must be very controlled. Everyone must be sitting on a chair at a table, say please and thank you for drink and snacks; and they have 3 minutes to eat it, then they are cleared away, so there are no possibilities to spill drinks.
Make sure you give the children jobs and responsibilities, and thank and praise them at every possibility.
You may want to set up a star chart of some sort where the children get to colour in a square each time you want to reward them. Many boys are very competitive, and will go for this in a big way. Then look for every opportunity to praise and reward them, rather than to criticize and tell them off.
You will probably find that as they spend more time in reception at school that they soon settle down and become easier to manage.
FINALLY! Just think of your dd's poor teacher at school who has to manage 30 children all day every day, and buy him/her a big Christmas present