You won't find any 40 year old graphics designer for the same reason you don't find a 40 year old programmer. These are considered basic level skilled jobs that labour supply is in abundance all over the world.

Generally studios are not interested in paying twice the amount for and oldie when there is an inexhaustible supply of younger and far cheaper workers who are willing to take even more brutal hours and punishing work stress. The amount of junior/fresh graphics designers from China/India/Korea and now even Vietnam is endless and this depresses wage levels.

IMO you only have 2 routes since you are already 30. Either you find a niche in the creative industry and branch out to do something on your own (freelance, sole proprieter, business consultancy owner) or move up to management level where skillset is more strategic. Going down the bare bones on the ground operations in graphic design will be a dead end for you in a few years and the fastest way to end up driving a taxi.

Of course if you are adventurous enough, you can always move back to corporate space, but with the age and lack of meaningful experience, it's going to be a tough sell. You will likely have to take up entry level sales or admin based executive jobs and that might mean a pay cut.