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