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