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