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