One vertex per element, one color per generator, with an edge from x to x·s.
(9,10,14,17)(11,18,21,15)(12,16,13,22)(19,24,20,23)(25,26)(27,35)(28,39)(29,31)(30,43)(32,38)(33,40)(34,42)(36,48)(37,51)(41,46)(44,50)(45,56)(47,49)(52,53)(54,55)(1,2)(3,7)(4,8)(5,6)(9,11)(10,15)(12,19)(13,20)(14,21)(16,23)(17,18)(22,24)(26,31)(27,36)(28,40)(34,43)(38,50)(41,55)(45,53)(47,51) involution — undirected(2,6)(7,8)(9,12,14,13)(10,16,17,22)(11,19,21,20)(15,23,18,24)(25,27,30,38,29,36,42,50)(26,32,34,35,31,44,43,48)(28,37,41,52,40,49,55,56)(33,45,46,47,39,53,54,51)(1,3,5,4)(2,7,6,8)(9,13,14,12)(10,16,17,22)(11,20,21,19)(15,23,18,24)(25,28)(26,33)(27,37)(29,40)(30,41)(31,39)(32,45)(34,46)(35,47)(36,49)(38,52)(42,55)(43,54)(44,53)(48,51)(50,56)(1,4,5,3)(2,7,6,8)(11,21)(15,18)(19,20)(23,24)(28,40)(33,39)(37,49)(41,55)(45,53)(46,54)(47,51)(52,56)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.