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