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