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