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