Vermiculite is what is used to incubate the eggs in. I would not even think of using it for her to dig in. Did she try to dig in it at all?
If you put an opaque container at least 12" deep x 12" x 8" filled almost full of moist (not wet) washed playsand in her cage and leave it there hopefully she will dig in it and lay her eggs if you have not left it too long. At the first mating they can lay earlier than the normal 30 days depending on when during the cycle you mated her.
You can use a trash can method too....but then how will you know when she's ready to lay the eggs? Are you just going to leave her in there? Moving her back and forth is not good.
If/when she is digging do not let her see you watching her or she may abandon the hole. If it happens often enough, it can lead to eggbinding.
I don't use a trash can. I use a 65 liter rubbermaid bin. I cut away most of the lid and screen over it. I fill the bin at least 12" deep with moist washed playsand and add a branch. I put the chameleon in when she has been digging in the container in her cage to show me that she's ready. I put the lid on and lay a UVB light over the screen. I can water her and feed her while she's in there if I have to...but I don't leave any uneaten insects in there in case they chew on her or the eggs. She should dig the hole until she's satisfied with it, turn around butt down and lay the eggs (often in the evening), fill the hole in, tamp it down and return to the branch...at which point she should be put back into her cage, fed and watered well. You can then dig up the eggs too.