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