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