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