Are there different symbols to identify the different types of fuels used for general aviation aircraft?
As Walker notes in his answer AvGas is typically noted by color when talking about telling it apart. In terms of aircraft markings for fuel this is governed by FAA FAR 23.1557 Miscellaneous markings and placards. and some more notes in this AC,
(c)Fuel, oil, and coolant filler openings. The following apply:
(1) Fuel filler openings must be marked at or near the filler cover with- (i) For reciprocating engine-powered airplanes - (A) The word “Avgas”; and (B) The minimum fuel grade.
These are fairly simple regulations to comply with so there is a wide variety of markings available, but the end results tends to be a decal looking something like this:
Above ground storage tanks will also have to comply with local state regulations on petroleum storage, here are the New Hampshire regulations as an example. Generally this will require an NFPA style decal but pilots dont really use those to identify anything. The typical signage for 100LL is a red back, white fount, all caps AVGAS 100LL this is common on tanks,
and trucks alike,
Its also important that you as the pilot are present for fueling both to verify type and quantity. If there is any doubt about what is in a truck or at a pump some should be pumped into a canister and verified by color before fueling an aircraft.
There is 87 Mogas, 100 Low Lead (100LL), and 130. 100LL is pretty common for the 4 and 6 cylinder general aviation aircraft (single and 2, 4, 6 seaters with one and two engines).
87 and 130 are getting less and less common. I don't think I've ever seen 130, altho my plane is placarded to use 100LL or 130.
Larger planes than that and you start seeing Jet A fuel used in single engine and twin turboprops, turbine, and turbofan equipped planes.
For example, in western NY, you can see prices in the Buffalo area for Jet A, 100LL, and Mogas: http://www.airnav.com/fuel/local.html enter BUF or KBUF. You can try other areas also, such as LAX (Los Angeles), FTW (Fort Worth), JFK, STL (St Louis).