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