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