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