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