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