One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,4,6)(3,5,7,8)(9,10)(11,18)(12,21)(13,16)(14,17)(15,20)(19,23)(22,24)(25,26,30,33)(27,35,38,48)(28,32,39,46)(29,41,43,34)(31,42,45,37)(36,49,50,56)(40,53,52,47)(44,54,55,51)(1,3)(2,5)(4,7)(6,8)(9,11)(10,15)(12,19)(13,22)(14,20)(16,23)(17,18)(21,24)(28,39)(32,46)(36,50)(40,52)(44,55)(47,53)(49,56)(51,54) involution — undirected(3,7)(5,8)(25,27,30,38)(26,31,33,45)(28,36,39,50)(29,42,43,37)(32,44,46,55)(34,48,41,35)(40,54,52,51)(47,56,53,49)(9,12,14,13)(10,16,17,21)(11,19,20,22)(15,23,18,24)(25,28,30,39)(26,32,33,46)(27,36,38,50)(29,40,43,52)(31,44,45,55)(34,47,41,53)(35,49,48,56)(37,51,42,54)(3,7)(5,8)(9,13,14,12)(10,16,17,21)(11,19,20,22)(15,24,18,23)(26,33)(28,39)(31,45)(34,41)(35,48)(36,50)(40,52)(51,54)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.