Aluminium screws should not be used with pressure treated wood, and galvanised screws should not be used with Cedar. The tannic acid in the cedar reacts with the galvanisation.
The photo shows special cedar coloured screws who's coating helps to resist rusting. Type 18-8 stainless steel would be the best for corrosion resistance, but they will look far to shiny. If you want to not see the screws at all, you can get special brackets that go under the deck, allowing you to drive your screws up at an angle from below -- now no screws will show.