Is there a link that shows all active offers?

Yes.

Through the Campaign Builder

Go to Campaigns>Regular, and then click on Create Campaign>New Campaign.

Choose Text Message as the campaign type and click Next.

Give the campaign a random title and click Next again.

Now click on Insert Variable, then choose Offer Page.

Your link will be in the preview section on the right-hand corner.

Note: Alternatively, you can skip creating the new campaign part and choose an existing campaign to get the link. (Campaign must be in draft for you to be able to edit)