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