The map shows only 138 electors but there were 276 total votes. The two totals are unequal because the map shows the number of states electors and not the number of ballots casted by each elector. Each elector was allowed two votes- but the votes did not specify if they were for President or Vice President.
This resulted in Jefferson and Burr (Democratic-Republican party) initially tying for president with 73 votes each. The House held a tie breaking vote with each state casting one vote for President.