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