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