Character styles used place.

Edit>Find and Replace

In the Find Format box - you can click on this - and then select your character style

Then hit Find

You can then find the character style

alternatively - you can could add a new colour to your document temporaily

and then change your character style by editing it - and using this new colour

this would provide a visual guide on each page

You can then delete the swatch when finished and you'll be asked to replace the swatch

replace it with the swatch that it was originally.

You can also use the Story Editor

Which can give a view on the left of each style in use. But it can be a bit slow on large documents.