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