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