My best advice would be to use the charts of one of the largest exchanges - maybe Bitfinex? That will only show the bitfinex volume of course.
Do they show BCH trading volumes? Do you have any link to share?
Actually, you don't even need to register on bitfinex. You can just use the "view demo" link on the front page and view and use their charts.
Yes they have trade volume in the charts. You can make a non-verified account (no ID required) for free and use their charts. No need to fund the account. Bitfinex.com
