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