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)(11,14)(12,19)(13,16)(15,20)(17,23)(18,22)(21,24) involution — undirected(2,5)(6,8)(9,11,13,18)(10,14,16,22)(12,17,20,24)(15,21,19,23)(25,26)(27,33)(28,32)(29,31)(30,34)(35,39)(36,38)(37,40)(1,3,4,7)(2,6,5,8)(9,12)(10,15)(11,17)(13,20)(14,21)(16,19)(18,24)(22,23)(25,27)(26,30)(28,35)(29,34)(31,33)(32,37)(36,40)(38,39)(12,20)(15,19)(17,24)(21,23)(26,31)(27,34)(32,38)(35,40) involution — undirected(10,16)(14,22)(15,19)(21,23)(27,34)(30,33)(35,40)(37,39) involution — undirected(25,28,29,36)(26,32,31,38)(27,35,34,40)(30,37,33,39)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.