MySQL Simple pivot table with MAX(), GROUP BY and only_full_group_by
If you want ties, i.e. when an employee has two jobs on the same day, that happen to be the latest one display both, you can join a derived table with query doing the aggregation.

SELECT ej1.*
       FROM employee_job ej1
            INNER JOIN (SELECT ej2.employee_id,
                               max(ej2.created_at) created_at
                               FROM employee_job ej2
                               GROUP BY ej2.employee_id) ej2
                       ON ej2.employee_id = ej1.employee_id
                          AND ej2.created_at = ej1.created_at;


If you want to eliminate ties and say you want the one with the largest ID in such a case, add another level.

SELECT ej1.*
       FROM employee_job ej1
            INNER JOIN (SELECT max(ej2.id) id
                               FROM employee_job ej2
                                    INNER JOIN (SELECT ej3.employee_id,
                                                       max(ej3.created_at) created_at
                                                       FROM employee_job ej3
                                                       GROUP BY ej3.employee_id) ej3
                                               ON ej3.employee_id = ej2.employee_id
                                                  AND ej3.created_at = ej2.created_at
                               GROUP BY ej2.employee_id,
                                        ej2.created_at) ej2
                       ON ej2.id = ej1.id;