There are lots of ways but not all may suit you or you may not think them appropriate.
Don't make any judgy comments about the parenting skills - they are just finding their way like you did. Instead, praise and be positive. And always say nice things about them to your dgd.
Don't be grabby with the baby. There is nothing more insensitive than a gp who just whisks the child off a new, hormonal mother. The new mother will react like a tigress!
Don't act like your dgd is all you're interested in. That's quite insulting. Show interest in the parents too. And if you take photos, please don't edit out the parents!
Offer to babysit or have the child around for a morning. If the answer is no, don't push it. Just wait and be patient. It may well happen in time.
Be helpful. Take round a casserole. Offer to help clean and babysit. Do the washing up.
Don't focus your life on your dgd. She's not there to keep you busy or entertained in your old age.
All in all, make your presence a positive, enthusiastic, helpful one. Not a broody grandma who wants to relive her parenting days.