Take hwy 41 North toward Yosemite. You will begin to see signs along the road telling you to "Ride the Logger." Just on the other side of Oakhurst you will see the driveway on the right side of the highway for the "Logger." It is a museum commemorating high Sierra railroad logging operations including a restored shay from the old Westside Lumber Co pulling passenger cars for tourists. If memory serves, it is about 45 minutes to 1 hour North of Fresno on hwy 41.
If you have time to to drive about 150-200 miles on a weekend, go to Jamestown. There are two primary routes you can take. Probably the fastest route is to go North out of Fresno on hwy 99 to Turlock. At Turlock, take hwy 165 also called J14 to the town of Oakdale. In Oakdale go Northeast on hwy 108 to where it joins hwy 49 and follow 49/108 to Jamestown. The more scenic route is to take 41 Northout of Fresno to Oakhurst and turn left in Oakhust on hwy49. Be aware that 49 is a twisting mountian road most of the way North. It is a good highway, but if you are nervous about driving over mountain roads, you might prefer to take the other route. Yo will encounter mountain roads either way, but not as many by going North on hwy99. In Jamestown is the Railtown 1897 State Historical Park. It was the old headquarters of the Sierra Railroad, there is a train ride, tours through the old railroad shops, and such.
Another trip that will take a couple of days to do is to go about 4 hours North of Fresno on hwy 99 to Sacramento to the California State Railroad Museum in Old Sacramento. If you go to the Museum, when you get your ticket to go in you can walk right into the museum, but don't. Take the time to walk up the ramp to the movie theatre and go to the 10-15 minute introductory film first. When the film ends you will then enter the Museum through a life size diorama of a tunnel being blasted out of solid rock in the Sierra Nevada Mountains complete with Chinese "powder monkeys" hanging off the walls to plant their charges and the Leland Stanford 4-4-0 locomotive. In my opinion it is the most impressive way to enter any railroad museum. As you then walk past the Stanford, you go out of the tunnel into the first floor of the museum.
Farther North from Sacramento is the town of Porterville, home to the Western Pacific Railroad Museum. There you can even have the chance to operate a real deisel locomotive on the museum grounds. I'll post a few links:
www.wplives.org
www.californiastaterailroadmuseum.org
I tried google for the Logger, but it looks like they do not have a web page, but the Shilo Inn in Oakhurst promotes the Sugar Pine Railroad/Logger on their web page.