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