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