A quadratic upper bound on the reset thresholds of synchronizing automata containing a transitive permutation group

For any synchronizing n-state deterministic automaton, {C}ern\'{y} conjectures the existence of a synchronizing word of length at most (n-1)². We prove that there exists a synchronizing word of length at most 2n² - 7n + 7 for every synchronizing n-state deterministic automaton that satisfies the following two properties: 1. The image of the action of each letter contains at least $n-1$ states; 2. The actions of bijective letters generate a transitive permutation group on the state set.