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