We have as of yesterday made this requested change and made the cancellation button more prominent. (screenshot below)
We have made some other changes to the page which your customers will be directed to when processing cancellations or confirming their reservation and the release notes for this are here -> https://sales.resdiary.com/release-12-5/
Thanks for getting in touch.
We are working on the edit / cancel options on ResDiary.com at the moment and one of our aims is to make the options available as clear as possible to the diner.
I will update when we have completed this project.