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