The best way is to not do it in SolidWorks.
SolidWorks is solid modeling software with some drafting capability. Any sort of 2-D drawing/drafting/whatever you want to call it is a PITA in SolidWorks. You'd do better using DWGeditor or (if you have it) Visio. Visio is specifically designed for schematic type prints.
I agree with Josh that these types of diagrams are best done in Visio, or something similar. The "pro" version of Visio comes pre-loaded with a full library of pneumatic schematic (hey that rhymes!) symbols. You can then insert your Visio diagram as an OLE object in the Solidworks drawing.
However, to answer your question:
You can go ahead and just start sketching in drawing mode. First create an "Empty" view. (Insert > Drawing View > Empty) and place your sketch entities in there. This will "group" everything to make it easier to move things around en masse. I presume you know about the SW Block functionality? If not, check out the SW help on blocks; it'll save you a lot of headaches.
Some manufactures have symbol DXFs on their websites. For instance:
This would be a good start to build your own SW symbol library.