We do not supply coloring book images for your to fill a book. This is something you need to create yourself.
You can make them yourself to use in your book.
Ask friends and family if they have any artistic talent, if so, if they would be interested in doing coloring book pictures for you. Offer them a perrcentage of the sales, flat rate, or hopefully a good friend who will do for free!
You can also try going to the website, Upwork or Fiverr. Hire artists to make them for you. Be sure to tell them you don't want someone else's they have made and that the ones they create for you are only for you.
To learn more about Upwork and the whole process we have an article in the Book Bolt Blog called "How To Use Upwork To Outsource And Scale Your KDP Business" you can read.