One vertex per element, one color per generator, with an edge from x to x·s.
(9,10)(11,15)(12,20)(13,14)(16,22)(17,19)(18,24)(21,23)(25,26,31,36)(27,37,39,32)(28,34,29,33)(30,35,40,38)(1,2,5,4)(3,6,7,8)(9,10)(11,17)(12,16)(13,14)(15,19)(18,24)(20,22)(21,23)(25,27)(26,32)(28,38)(29,35)(30,33)(31,39)(34,40)(36,37)(2,4)(6,8)(10,14)(15,17)(16,20)(23,24)(25,28,31,29)(26,33,36,34)(27,38,39,35)(30,37,40,32)(3,7)(6,8)(9,11)(10,15)(12,21)(13,19)(14,17)(16,24)(18,22)(20,23)(25,29,31,28)(26,34,36,33)(27,38,39,35)(30,37,40,32)(1,3)(2,6)(4,8)(5,7)(9,12,13,22)(10,16,14,20)(11,18,19,21)(15,23,17,24)(25,27)(26,32)(28,38)(29,35)(30,33)(31,39)(34,40)(36,37)(1,4,5,2)(3,8,7,6)(9,10)(11,15)(12,16)(13,14)(17,19)(18,23)(20,22)(21,24)(25,30,31,40)(26,35,36,38)(27,33,39,34)(28,32,29,37)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.