This is both a hardware problem and a software problem. I'll focus on the hardware part, and also talk briefly about how to select one of your IR sensors once you've built the hardware.
Assuming the CD4051 only multiplexes 8 channels you'll need to build a 2-level multiplexer in order to be able to select one of 64 IR sensors.
You would attach the output of a top-level CD4051 to your Arudino. Then you'd attach each of the inputs from that first CD4051 to the output of another CD4051. You'll need a total of 9 CD4051's. You'd use a 3-bit input to the top-level CD4051 to select one of the 8 second-level multiplexers. You could then tie the 3 channel selector lines of each 2nd level CD4051 together. (You'd tie the Channel select pin As of all 2nd level CD4051s together, all channel select pin Bs together, and all channel Cs together).
The 3 control pins from the top level CD4051 and the 3 control pins from the 2nd level CD4051s would be connected to 6 digital outputs of the Arudino and serve as a 6 bit channel selector. which would select one of the 64 input pins on the 2nd level CD4051s.
To select 1 of 64 inputs you'd set the 3 bits to the top-level CD4051, which would select one of it's 8 input pins, which is in turn connected to one of the 8 second-level CD4051's. The 3 control bits to the 2nd level CD4051 would select one of the inputs to the active 2nd level CD4051. (It would select one of the inputs on ALL the 2nd level CD4051s, but only the selected 2nd level CD4051's output would be fed to the top-level CD4051, and forwarded to the Arduino.)
Once you've rigged your 9 CD4051s this way, the 3 bits from the top-level CD4051 and the 3 bits from the 2nd level CD4051 would serve as a 6-bit address of one of 64 inputs. You'd then wire your 64 IR sensors to all 64 inputs of the 2nd level CD4051s, and write Arduino software to use the 6 digital outputs pins to output the 6-bit address of the desired IR sensors into the CD4051 multiplexer array.