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