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