I am no expert and opinions will vary on substrates, but I would not use the large piece cypress mulch that you get at a garden shop for the very reason you stated. It is an ideal substrate for redfoot tortoises but not for tokays. They do make a smaller piece cypress mulch for reptiles called "Zoomed forest floor bedding" which I think would work great for tokays. Petsmart sells it.
Here is the link. You will have to copy and paste the link....

http://www.petsmart.com/global/product_detail.jsp?PRODUCTprd_id=845524441777404&FOLDERfolder_id=2534374302030043&ASSORTMENTast_id=2534374302023694&bmUID=1171830562551&itemNo=19&In=Reptile&N=2030043&Ne=2