There was also a simultaneous special election for the remainder of the current term. Findley did not run in that election.
Candidates' party affiliations obtained from the 9/19/1857 Placer Herald (of Auburn). https://www.cdnc.ucr.edu/?a=d&d=PH18570919.2.2&srpos=38&e=-------en--20--1--txt-txIN--------
Source for Popular Vote data: California State Archives, "For State Treasurer Full Term," Statement of the Votes Polled in the State of California, on the Second Day of September, A.D. 1857 (Sacramento, 1857)